Reborn's past is shrouded in mystery, though it can be assumed that at some point in his life he had built the reputation as the world's strongest hitman, which had happened even before he met his fellow Arcobaleno. He was said to be quite close to first Arcobaleno boss, Luce, and at an unknown point in time, he began working for Timoteo.
Reborn was cursed by Checker Face, transforming himself to an infant and given the Sun Arcobaleno Pacifier. After being cursed he enlisted Shamal in helping in "erasing' his past self and giving "birth" to him.
Sometime after infliction of his curse, Reborn became the home tutor for Dino and trained him to become the Tenth Boss of the Cavallone Famiglia. He eventually left for Japan to train Tsuna, there were still many things that Dino wanted to teach him.
During an unknown point in his life, he became a famous mathematician, going under the name "Borin", and solved math problems that were previously considered impossible. Though, it's also possible that his "Borin" persona could have been a look alike. Reborn was previously in a relationship with four different women, his most recent lover being Bianchi.
Reborn is introduced as Tsuna's home tutor after Nana found his flier. He then reveals to Tsuna his true intention and Tsuna's relation to the first Vongola Boss, helping him to befriend Kyoko in process.
Throughout the arc, Reborn mostly takes a mentoring back seat in the arcs, rather than the direct fighting; however, he can be credited with helping Tsuna achieve much higher levels and gain new, more powerful attacks. And he is shown wearing many costumes and appearing in his many hideouts. He is a known celebrity at Mafia Land.
List Countdown Edit
Before he learns of the seriousness of the attacks, Reborn, along with Nana encourages Tsuna to learn how to defend himself. But when he and Tsuna visit the hospital after Ryohei falls prey to the attacks, he discovers the watch. When Leon's tail falls off, the severity hits him. He reads Tsuna the letter he received from the Ninth, and opts to gather a group to do battle with Mukuro's gang.
Kokuyo Land Invasion Edit
Bianchi, Yamamoto, and Gokudera join Reborn and Tsuna as they begin their offensive. During Takeshi's bout with Ken, he kicks Tsuna into the Botanical Dome because he expressed concern over Takeshi. He helps the two out of the hole after Takeshi wins the fight and accompanies the group to a rest area, where he sleeps through the encounters with M.M. and Birds. When Reborn awakens, Tsuna runs off to go and pursue Futa, and the rest of the group stays behind to take on the next killer, who turns out to be the Fake Mukuro. When Gokudera is temporarily incapacitated by Shamal's Trident Mosquito side effects, he watches as Yamamoto takes on the Fake Mukuro. He and Takeshi simultaneously figure out and reveal the trick of the Steel Serpent Ball. But, it wasn't enough for his future pupil to win. As Bianchi steps to the plate to fight next, and is nearly pulverized, Reborn shoots Tsuna with the final Dying Will Bullet just before he catches the weapon. Reborn looks on as Tsuna takes the win, and as Lancia reveals that Mukuro is actually still up ahead.
Mukuro Face-off Edit
Reborn is forced to condone leaving Gokudera behind to take on Chikusa and supplies Tsuna with the whip Dino gave him. He mainly observes as Tsuna frees Futa from possession and gains his new X-Gloves to battle with Mukuro, only intervening when Tsuna panics in the midst of the fight, and he has to talk some sense into him.
Reborn, during the down time between Ring Battles, trains Tsuna on how to use the Dying Will Zero Point Breakthrough in order to take on and defeat Xanxus. However, when Hibari returns from training after Hayato's Storm Ring Battle, to bite everyone-Varia and Tsuna's Family- to death, Reborn placates him by promising that he may be able to battle Mukuro again, which greatly pleases Hibari. For the remainder of the Arc, Reborn has a mainly static role of training and commenting. He lastly shoots Tsuna at the start of the fight when Xanxus tries to gain a cheap shot before the match starts and watches as Tsuna's Family proves victorious in the Sky Battle.
Arrival & The Search for the Strongest Edit
Reborn is the first to be transported to the Future and trapped there. It is not yet revealed how he found his way to the Vongola Headquarters, but he is next seen greeting Tsuna and Gokudera as they arrive there with Lal Mirch, though he has to wear a special suit to keep from being killed by the anti Tri-ni-sette radiation that Byakuran is pumping into the atmosphere. The anti Tri-ni-sette radiation affects the Arcobaleno severely, paralyzing their movement and killing them slowly, but it does not seem to have an effect on normal people. Reborn reveals to Tsuna that he needs to gather all seven of his guardians to do battle with Byakuran's forces. Reborn doesn't venture out of the base at all during this plotline due to the radiation. He does, however, help Tsuna with his training after he returns with Kyoko, Haru, I-Pin, Lambo, and the Yamamoto from 10 years ago by getting Tsuna to realize what his true goals are, which were to "protect everybody," not "to return to the past."
Merone Base Invasion Edit
Reborn appears after Tsuna is captured by Spanner as a hologram projected by Tsuna's headphones and witness to Spanner instructing Tsuna on how to use the contacts to perfect his X-Burner. He remains with Tsuna for the rest of the invasion, and gets Giannini to program a holographic distraction during Tsuna's fight with Genkishi. When Shoichi Irie reveals that he is an ally of the Vongola, Reborn believes him, mostly because he answered the questions that Reborn had being thinking about since he was sent to the Future.
As Tsuna and his Family are sent back to the past, Reborn tells them the few Abilities and characteristics of the Arcobaleno. He also remembers that the current Sky Arcobaleno is missing, which may become a predicament for Tsuna in the Future Trials. He also reminded Tsuna that he is also an Arcobaleno, in which he says that he would not hold back during the Trial.
During Reborn's Arcobaleno Trial, he informs Tsuna that his Trial was a seven-on-one, all-out battle with him, and that all six of the Guardians, including Lambo, were to participate. He knocks out Tsuna and takes down Hibari, Chrome, Ryohei, Gokudera, and Yamamoto. When Tsuna finally comes to, the sleeping Lambo is the only one who was in a good condition.
Tsuna at first does not want to fight Reborn, but Reborn tells him that he's still "too soft" and that his fallen comrades are his responsibility. Tsuna finally accepts this and enters Hyper Dying Will Mode and fights Reborn. Reborn allowed himself to be beaten into a wall but Tsuna stops as he is about to use his X-Burner and gets shot down by Reborn's Chaos Shot, who said "I cannot pass a person not fit to be Boss."
He gets captured by Verde, along with all the other Arcobaleno besides Aria, using a variation of anti Tri-Ni-Set waves, which only paralyzes them, as opposed to outright killing them. After Verde's trial, he was asked for a second chance at his trial by Tsuna, but he said that it wasn't necessary. He states that they completed it in their fight with Verde.
To prepare for "Choice," the war game that Byakuran is making the Vongola Guardians play, Reborn asks Shoichi to explain the rules. While he finds the game tasteless, he has great faith that the technicians will come up with solutions for the problems they will be facing. One of their solutions was to make the Guardians ride Motorbikes for extra mobility. When explaining to Tsuna how to ride, he instructs Tsuna to pop the clutch without Tsuna realizing that it was wrong. Reborn's reasoning is that Tsuna should get the worst parts over first that is his tutoring method.
When Dino arrives at the Vongola Headquarters and assigns the Guardians their tutors, Reborn assumes the role of "Tutor Fairy," mostly likely only so he can discipline Dino if he makes any mistakes.
Reborn is present during Yamamoto and Hibari joining the group in the moments before Choice begins. He sees them all unleash their Vongola Boxes and generate twice the amount of FVs needed to transport them- a whopping 10 million. He is engulfed in a beam of light along with everyone else present.
He wakes up in the Lightning Field that Tsuna selected, and listens as Byakuran explains the rules of Choice more clearly. Reborn, along with the rest of those chosen to sit out of the first battle, relocate to the Vongola Audience Stalls to watch the battle of Tsuna, Gokudera, Yamamoto, Shoichi Irie, and Spanner for the Vongola versus Kikyo, Saru, Torikabuto, and Deisy for the Millefiore under the Target Rule.
Later, he protects Uni from Byakuran by shooting him, saying that if he lays a finger on the Arcobaleno Boss, he won't sit back and watch.
Seeing that Tsuna and the others need to become stronger, Reborn arranges to have them sent back to the past. While in the past, Reborn gathers the other Arcobaleno to train Tsuna and his friends. He is also the one who explains to them that they will be tested by Vongola Primo's Guardian. Reborn will train Ryohei, as they both have Sun Flames.
Reborn begins to stay to Ryohei's and Kyoko's house as being Ryohei's temporary tutor.
Reborn was an audience to Yamamoto's trial.
It was stated by Reborn that because Lampow hid inside a castle inside the amusement park and the only objective was for Lambo to acquire three stamps and go to him, it shows his obvious distaste for Lambo and the fact that he had not prepared beforehand. He goes to the amusement park with Lambo, Tsuna, Gokudera, and Yamamoto. Verde finally shows up himself, after sending all sorts of tests on Lambo and defeated by Lambo's Elettrico Cuoio. Reborn chides the defeated Verde and tells him that he is a tutor and should not do this to his student.
During Gokudera's trial, Reborn is seen sitting on Namamori School roof top discussing with Fon, Colonnello and Skull on their counterpart students. Skull tries to brag about him and Hibari, but the rest of the Arcobaleno there ignores him. As Skull repeats his sentence many more times, Reborn calmly takes Skull and throws him off.
During Hibari's and Ryohei's trial, Reborn tricks Skull into taking action on Hibari. When Skull tries to attack the school, he tells Tsuna, Gokudera and Yamamoto not to interfere with Hibari and Ryohei arguing and later, defending the school. Eventually, Reborn told Yamamoto to tell the first-year base ballers to evacuate from the school.
After arriving back with the rest of the gang from the past, Reborn tells Tsuna that they do not have much time before the Real Six Funeral Wreaths appear from the teleportation system. Soon after Giannini gets the alert that they have arrived, Reborn goes and inform the rest.
He flees the Vongola Base together with the rest as Squalo tries to buy time by fighting with Zakuro. Upon hearing Haru's suggestion of a hideout, he decides to agree into hiding at the place Haru knows of.
Upon reaching the place, which turns out to be Adult I-Pin's ramen customer's place, (uncle) Kawahira suspiciously tells them that he knows what is going on and they can trust him on luring away Zakuro. At first, Reborn was suspicious but decides to trust him. When Kawahira uses his Segno Hell Ring to create fake killer intent to lure Zakuro away, Reborn starts to ponder who exactly Kawahira is, he is being able to create strong illusions too.
When Kikyo, Bluebell and Zakuro arrives to take Uni away, Reborn joins in Gamma and Tsuna in defending Uni. Reborn sits on Basil's Alfin to travel to the air to help out, shooting at Kikyo, tell him that the Vongola do not fight alone but as a team. With that inspirational sentence, the rest of the Guardians become prepared to fight against Kikyo, Bluebell and Zakuro. Kikyo decides to retreat, leaving Reborn and the others behind.
Fleeing into the forest according to Uni's suggestion, he tells Tsuna that he has to come up with a plan to continue protecting Uni from Byakuran. After seeing the slight conversation between Uni and Gamma, Reborn decides to talk to Gamma about his feelings for Uni. As Gamma and Reborn walk away from the camp, Reborn tells Gamma that he should stop treating Uni like a child and admit her feelings towards him.
When the Tri-ni-sette set ring bosses, the Mare and the Vongola calls, Uni's Sky pacifier resonates and she floats upwards. Determined to protect the Arcobaleno's boss, Reborn tries to break the barrier around Uni, only to get deflect off.
Reborn gets a notice from the 9th Boss that the inheritance ceremony would start in a week's time.
Investigating the Simon Famiglia Edit
Reborn, getting suspicious, uses the opportunity on the Simon Famiglia guarding Tsuna to test Kouyou Aoba (since it was his turn). Just nice, Ryohei appears at Tsuna 's house, following Kouyou's taunts on a piece of paper. Upon Nana's suggestion, he decides to give the friendly rivals a study test (which they share the hatred of studies, both being 'idiots'). He gives them an easy test written on extra hard plates. He slyly tells them that if they manage to break the plates, he would have to postpone the test. He watches over the duration of the two spending time in Tsuna's room. When Tsuna's room explodes, he rushed up with the rest to see the plates broken by Ryohei's Maximum Cannon. He was impressed by Ryohei's strength but was more shocked by Kouyou being able to withstand Ryohei's Maximum Cannon without receiving any injuries.
Arrival at Simon Famiglia Island Edit
Reborn arrives at the island with Tsuna, Gokudera, Lambo and Ryohei on the Ninth's boat with his guardians. He debarks with Tsuna and his remaining guardians to the island. When Tsuna activated his new Vongola Gear when the Simon Famiglia arrived, Reborn felt that Tsuna feels different.
Ryohei Sasagawa vs Kouyou Aoba Edit
Reborn, together with Tsuna, Gokudera and Lambo could only stand at one side and watch the fight between Ryohei and Kouyou.
First Key Edit
After Ryohei and Kouyou collapse because of the severity of their injuries, Tsuna, Gokudera and Reborn rush to their side to provide medical attention. However, the Vindice intervene, declaring that since both combatants lost, they were both to be imprisoned in the Vindice Prison. Reborn doesn't receive the memories contained in the First Key.
Hayato Gokudera vs Shitt P! Edit
After the Vindice take their leave, Reborn with Tsuna, Gokudera and Lambo carry on walking on the road. Soon, they reach a town which looked like the town Giotto and G met Simon. There, they meet Shitt P!. Reborn observes the battle between Shitt P! and Gokudera. He was impressed when Gokudera wasn't disillusioned on Tsuna and still insists on becoming Tsuna's right-hand man, trying to live it up to G
Tsunayoshi Sawada vs Enma Kozato Edit
Shortly after Shitt P's, defeat, Enma furiously ambushed Tsuna, forcing Tsuna to fight back. However, Enma then revealed that Iemitsu was the one who killed his family, shocking Reborn, Tsuna, and Gokudera. This revelation caused Tsuna to lose his will to fight and nearly killed if Enma's Simon Ring didn't lose control. This made Enma has no choice but to retreat. Reborn immediately approach Tsuna, asking whether he is okay. Seeing Tsuna didn't respond to his question, Reborn kicked him to get his attention, but realised that Tsuna was too depressed by the revelation.
Kyoya Hibari vs Adelheid Suzuki Edit
On their way, Reborn states his suspicion of Enma's sudden attack and suspected that there's a possible black shadow that controlling the Simon from behind the scene. Reborn further comments that Simon is not monolithic, angering Adelheid who overheard it. He, Tsuna, Gokudera, and Lambo then watched her battle against Hibari, which resulted with the latter's victory. Once receiving the fourth key, Reborn concludes that there's someone who wanted Cozzato to be killed by sending the fake letter to him. This proven to be true when Julie, who revealed himself to be Demon Spade possessing Julie's body, admitted himself to be the culprit behind everything that had happened.
At this revelation, Kaoru attacked Demon, but later turned out the one he stabbed was an illusion created by Demon, who stabbed back Kaoru from behind. To prevent Tsuna and his friends attacking him all at once, Demon ordered Chrome to trap Tsuna, Gokudera, Hibari, Reborn, and Lambo with her mist barrier, preventing them from interfering. Yamamoto then arrived to save Kaoru, with the latter being imprisoned by the Vindice since he had lost his pride, allowing them to witness the fifth key that shows Cozzato and his Family survived from Demon Spade's scheme thanks to G and the other remaining Guardians who were sent by Giotto after realizing Demon Spade's plan. This revelation shocks everyone and makes Reborn wonder why there's no clue about Cozzato's survival.
After Demon and Chrome decided to retreat, Reborn asked what Tsuna will do regarding Iemitsu killing Enma's family, which Tsuna answered that he will believe in his father.
Tsunayoshi Sawada vs Enma Kozato (Rematch) Edit
At Simon Castle, Tsuna confronts Enma who was too overwhelmed by hatred, leading him no choice but to fight him. After much struggling, Tsuna able to save Enma from his out control Flame and received the sixth key, which is a clear pacifier that shows Cozzato decided to hide within shadow to fool Demon and swore to Giotto that the Simon Family will always be there to support the Vongola. The oath made by the two bosses led a Vindice with a baby who holds the clear pacifier to appear before them to uphold the mafia law. Reborn immediately asked where the Vindice got the pacifier, but they refused to answer.
Tsuna & Enma vs Demon Spade Edit
Reborn and the others went to the circular building where Mukuro is and finds him apparently already defeated Demon. Unfortunately, this turned out to be planned by Demon, who lost on purpose in his battle against Mukuro so he can possess Mukuro's body in the Vindice Prison before Mukuro could return. The Vindice appears and tells that Demon has staged a prison break and since Demon Spade's actions are based on his dedication for Vongola, the Vongola must be the ones to defeat him in exchange they will free Ryohei and the other Simon Guardians.
Demon reappears, powering up with the five Simon Rings he has stolen from the prison, trapping Gokudera, Lambo, Yamamoto, and Julie inside his illusionary worlds in the process. Hibari challenged him to a one-on-one fight, which led to Hibari be trapped as well. Tsuna and Enma decides to fight together and with Chrome and Mukuro's help eventually able to blast Demon with XX-Burner. However, it turns out Demon barely survived the attack and proceeds to crush Tsuna's bones to pieces. This angered Reborn who wished to help his student, but the Vindice threatened that if he interferes, they will be his opponent.
Just before Tsuna was killed, Enma's Simon Ring merged with Tsuna's Vongola Ring, granting Tsuna the power strong enough to defeat Demon.
Reborn is shown to be having a dream of the time when a mysterious man gathered the "I Prescelti Sette", the aforementioned group becoming the Arcobaleno as a result. In the dream, he recalls the experience but is suddenly turned back into his infant body. The mysterious man that gathered them reveals himself and presents them with the opportunity to turn back into their adult forms with a competition, where the strongest Arcobaleno's form will be reverted. Reborn resisted at first, but after his Arcobaleno colleagues, all agreed, agreed as well. Later, he asks Tsuna and Dino, explaining the curse of the Arcobaleno after they agreed to fight for him. Reborn is then seen the next morning walking with Tsuna to school, while the Kokuyo Gang shows up, Verde revealing himself and the fact that he asked them to fight for him, causing Reborn to mentally comment that Verde and Mukuro together were a troublesome duo. Reborn is later on seen walking with Tsuna to Dino's hotel, later following Belphegor, who, upon their arrival, kidnapped Tsuna to Xanxus's office. As Reborn arrives, a man claiming to be the planner of the "Representative Battle of the Rainbow" arrives, introducing himself as Wonomichi and states that he would be explaining the battle, who does so. On the first day of the Representative Battle of the Rainbow, Reborn only goes up to Iemitsu and Colonnello after Tsuna is defeated by Iemitsu to form an alliance with them.
On the second day of the Representative Battle, Reborn takes Team Reborn, his team, to Team Uni's mansion to hear some intel about Team Verde, who were immensely powerful on the first day of the battle. Night soon falls, and the battle begins, with Reborn and Uni sitting in the mansion while their representatives fought. When Iemitsu terminates his and Team Reborn's alliance, Reborn is visibly angry. When Reborn attempts to stop Colonnello's Maximum Rifle shot along with Gamma and Tsuna, Reborn preparing to release his Arcobaleno Curse, Byakuran intervenes and takes the blow. When Tsuna is defeated by Iemitsu and the latter is about to hurl a boulder at the former, Reborn, in his un-cursed form, intervenes and easily heavily injures Iemitsu, while teaching Tsuna a lesson about his two largest flaws in battle, though Tsuna is unaware who the un-cursed Reborn is. Reborn leaves his un-cursed form and watches as Tsuna fights Iemitsu.
During the third day battle with Team Bermuda, Reborn noticed that Tsuna hesitated to fight full power out of fear that doing so would destroy the boss watch. Seeing that Tsuna slowly getting cornered, Reborn shouted at him to forget about the boss watch and fight like his life depends on it. Reborn then took out Tsuna's 0 test score, revealing that the only reason he joined the Representative Battle is to make him stronger, Finally convinced, Tsuna prepared to continue to fight with all of his strength even if the boss watch breaks. Tsuna understands Reborn and both he and Jaque start to fight at full power. After Tsuna defeated Jaque, Bermuda comes because he wants to invite Reborn onto the team. Reborn rejects the offer. Bermuda von Veckenschtein created a warp hole and sucked Reborn with Tsuna too because Tsuna wanted to save Reborn. They both arrive in a place with skeletons on the floor. Reborn said that he let himself get sucked because Reborn wanted to know what Bermuda meant about "the truth." Looking up, Reborn and Tsuna see a stone revealing the secrets of the Arcobaleno.
Bermuda and Jaeger appeared in front of them and started to explain that the Arcobaleno are human sacrifices that Checker Face has set up to protect the Pacifiers from generation to generation. Once the Arcobaleno's life span start to reach to the end due to the curse, Checker Face will choose seven people to become the next Arcobaleno through either contract job or Representative battle and removed the flames of the previous Arcobaleno from the pacifiers, leaving them either to die or becoming Vindice. To get his revenge on Checker Face, Bermuda offered Reborn once again to join him. Reborn questioned why he choose him out of all Arcobaleno and what will happen to the current Arcobaleno if Checker Face was killed. Bermuda explained that he likes crazy people like him and witnessing Tsuna's growth through his teaching is what made him realized how Reborn is different from the other Arcobaleno. He revealed that if Checker Face is defeated, the current Arcobaleno, the Vindice, and everything that involved with it will die as killing Chekcer Face means destroying the Arcobaleno system itself. Reborn didn't mind dying, but he disagreed if Lal and Uni are getting involved with it. Tsuna, against the idea, declared that he won't let Bermuda win the Representative Battle. Hearing Tsuna's declaration, Reborn decided to follow Tsuna's will.
However, Reborn immediately changed his mind when Jaeger single-handedly overpowered Tsuna, seeing no possibility for Tsuna to win against him and told him that there's no need for Tsuna to die for them, the Arcobaleno since this is the Arcobaleno's problem alone. He told Tsuna that he can return the boss watch whenever he wants to. Once they got back, he immediately called the other Arcobaleno except Skull to a meeting and told them everything that Bermuda had told him. The meeting ended in a huge argument when Reborn considered joining Bermuda since he wanted to stop the Arcobaleno system even though it would be at the cost of his life while Colonnello doesn't want Lal to get into this and Mammon and Verde refused to die because of Bermuda's scheme. Uni and Fon tried to mediate them, but Mammon used an illusion that accidentally hit Uni. They finally stopped arguing, took Uni to the hospital and parted ways without making up.
In the morning, Reborn finds Tsuna and Tsuna says that he has something to tell him. Tsuna brings Reborn to Namimori Shrine, deciding to skip school. When Reborn says that as a home tutor he wouldn't permit it, Tsuna angrily rants about everything that had happened ever since Reborn came into his life and tells Reborn that he's not qualifed to be a home tutor. After his outburst, Tsuna states that he won't let Reborn die.
After Talbot manages to find a peaceful solution to the Arcobaleno's problem, Reborn remains as Tsuna's tutor. After pretending to have changed his mind about making Tsuna the next Vongola boss, he leaves for a few days and then returns with a declaration that he now intends to make Tsuna "Neo Vongola Primo", which is essentially the same as "Vongola Decimo", just under a different title. Reborn is last seen joining Tsuna, Tsuna's Guardians and the girls for a celebration. He is the last character seen by the end of the manga.