Hibari has a past that's never brought up and mostly shrouded in mystery. It's said that he lives in an enormous mansion with decorative structures similar to the bases in the Future Arc. Takeshi Yamamoto has heard rumors that Hibari's parents are from prominent families, but is unsure whether the rumors are true or not.
It can be assumed that at some point in his life, Hibari entered Namimori Junior High and became the leader of the Disciplinary Committee. It's unknown when this happened, with Ryohei Sasagawa admitting that Hibari was the chairman of the Disciplinary Committee since he first entered the school. Hibari has even mentioned to Tsunayoshi Sawada that he always picks whatever year he wants, making it hard to tell whether or not he truly is still a junior high student.
When Ryohei first met Hibari, he initially mistook Hibari as an ordinary student while thinking that Tetsuya Kusakabe is the rumored Hibari. Ryohei then always went to the school rooftop to accompany Hibari, assuming that Hibari might be lonely, and tried to befriend him, much to Hibari's annoyance. When Ryohei was beaten up right before the boxing tournament against Nobuyuki Middle School, Ryohei finally found out that Kusakabe is not the real Hibari. Hibari was present at the arena after Kyoko asked him to help them win the boxing match. He fulfilled Kyoko's request under one condition: after the tournament is over, Ryohei must never ask Hibari to join the boxing club. Ryohei agreed, and this explains why Ryohei has never asked Hibari to join the boxing club despite Hibari's reputation and strength.
Hibari reveals himself as the person who's using the reception room disciplinary committee and intimidates other committees that oppose him, unaware that an intrigued Reborn is watching him from a distance. When Reborn decides to use the reception room as a family hideout, Hibari is already inside. He promises to not let them leave unscratched for entering and Gokudera's smoking, then goes on to express his dislike towards weaklings and desire to beat them up.
Tsuna becomes Hibari's first victim, much to the anger of Hayato and Takeshi who make a failed attempt to defend themselves from Hibari. Reborn shoots Tsuna with a Dying Will Bullet, in order to help Tsuna face off against Hibari, but Hibari turns out to be stronger than most opponents Tsuna has previously faced. Tsuna does manage to hit Hibari with a slipper after getting shot with the Bullet, but the fight is quickly stopped by Reborn. Hibari is still in a bad mood and attempts to fight Reborn, who uses a bomb to make an escape. Sometime later, Hibari hopes to see Reborn once again, believing that he isn't a weakling.
Later, Dr. Shamal gave Hibari the sakura-kura virus so that Tsuna's Family could view the sakura in peace.
Due to the attacks on students of Namimori Junior High, Hibari went to Kokuyo Land to fight the gang's leader. He was later defeated by Mukuro, who took advantage of his Sakura-kura disease. He was imprisoned but later freed by Gokudera. Hibari then defeated both Ken Joshima and Chikusa Kakimoto and was given the cure to his illness. He then fought Mukuro again, but fell unconscious due to his previous injuries. Mukuro later tried to possess Hibari's body, but stopped due to the severity of the wounds.
Hibari was made the Vongola Cloud Guardian, but refused to be taught by Dino unless he could defeat him in battle. They fought in multiple environments so as to increase Hibari's fighting experience and so that he wouldn't see the damage done to the school. As a result, when Hibari reappeared after the Storm Ring Battle he was only calmed by the prospect of fighting Mukuro. During the Cloud Ring Battle, he appeared to defeat the Gola Moska robot and attempted to battle with Xanxus. However, Gola Moska once again became active and injured Hibari. During the Sky Ring Battle, he managed to resist the Death Heater venom but was injured while fighting Belphegor. He retired after rescuing Gokudera and Yamamoto.
In the Future, Hibari searched for information concerning Box Weapons by starting the Foundation. He also worked together in secret with the future Tsuna and the Millefiore Famiglia spy Irie Shoichi. Hibari later saved Gokudera and Yamamoto from Gamma. He agreed to train Tsuna, trapping him in his globe of Needles, resulting in a hallucinogenic state where Tsuna was granted his Inheritance. Hibari also helped Chrome draw out the power of her ring when her illusionary organs started to fail. Later, Hibari single handedly, defended the hideout against the Millefiore Raid (as instructed by Shoichi).
After this, he infiltrated the Merone Base and fought Genkishi. The two were evenly matched, though Genkishi gained the advantage when Hibari had no more rings to spare. As he was about to land a finishing blow, Hibari was replaced by his Past self (a fact that his future self was also made aware of). After receiving help from the injured Guardians and Kusakabe, Hibari was able to separate the group from Genkishi when his Hedgehog Box Weapon expanded at great speed due to the strength of his Dying Will Flames. He was later (along with the other Vongola Guardians) given a Vongola Box Weapon.
He later left the group and encountered the Future Dino, who began training him once again. After the Vongola lost the Choice battle, Hibari used his Vongola Box to slow down the Six Funeral Wreaths in order to help the Vongola escape.
Back in the future, Hibari and Dino faced off against Deisy at Namimori High. Deisy opened his Asura Box and defeated Dino. However, Hibari was able to defeat Deisy once he used his Cambio Forma and confiscated the Sun Mare Ring. He later appeared to be killed by Kikyo, though it turned out to be an Illusion created by Mukuro. Later, Hibari had his Dying Will Flames drained by Ghost (along with everyone else present). When Byakuran appears, he and the others could only watch as Tsuna fight Byakuran alone. After Tsuna defeated Byakuran, he and the others returned to the past.
After being sent back to the past, Hibari soon started arguing with a transfer from Simon Middle School, Adelheid Suzuki, about the control of Namimori Middle School. The next day, they started fighting in the rooftop but were stopped by Tsuna. At the Ceremony, he surprised the entire Famiglia with his murderous intent and the fact that he had decided to show up at all. He states that the people who have disturbed the peace of Namimori Middle will be bitten to death. Later, he along with the other guardians was defeated by Enma, and had their Vongola Rings broken. After the Simon Famiglia left, Dino asked him if he was all right. Hibari replied that he was, with the exception of his pride. Later, while Talbot was upgrading the Vongola Rings, Hibari waited in a different room from Tsuna and the others. Like the others, he was able to show his resolve and his Vongola Ring upgraded into Bracelet of the Cloud Version X. Upon arrival at the Simon Island, he watches the others from a helicopter. When Adelheid appears to challenge the Vongola Famiglia he appears from helicopter along with Kusakabe who left shortly. He accepted Adelheid's challenge, claimed that she could not bite him to death and revealed his Vongola Gear, Modified Uniform, starting the battle.
Before Hibari could attack, Adelheid encased herself in her Diamond Castle, claiming it was impenetrable. She then summoned 500 Blizzardroids, claiming that they all possessed the same level of skill as her and that they would take Hibari's arm band. Uninterested, Hibari calmly strikes down the first Blizzardroids that attack him using a Cloud Flame-enhanced chain shot out from his tonfas, much to Adelheid's surprise. Hibari then, after casually yawning, begins striking down the other Blizzardroids, switching between his tonfas, the chain, Roll and Alaudi's Handcuffs until all 500 have been destroyed. Undeterred yet surprised, Adelheid reforms several Blizzardroids behind Hibari, who dismisses them as not being a threat to him. Adelheid then asks Hibari why a man of his caliber has sided with Tsuna, and Hibari retorts that he isn't and asks Adelheid why she follows someone equally as pitiful. When Adelheid tries to defend Enma by saying he carries the sadness of Simon, Hibari remarks he is a small animal and that he keeps on screaming because he bears things too big for him. This sends Adelheid into a rage, who declares that Enma hates war and only chose this path to preserve the Simon, while sending her revived Blizzardroids to attack Hibari, who quickly cuts them down. Hibari then begins striking Adelheid's Diamond Castle, but his attacks seem to do nothing more than leave shallow cracks in the ice.
As Adelheid revives her Blizzardroids again, Hibari quickly defeats them and continues trying to break the castle, but Reborn comments that if Hibari continues at this pace he would run out of stamina. When Adelheid claims that Hibari will never break her castle and take her armband, Hibari says that in some cases, small animals aren't weaklings and have their methods of survival; otherwise they would have died out long ago. He then comments that Roll would be the one to shatter her castle from the inside; as Adelheid ponders what he means, it is revealed that Hibari planted copies of Roll in each crack he left. He then has Roll go into Needle Sphere Form and the copies inside the castle grow and shatter it. Hibari then appears behind a stunned Adelheid who says that despite her loss, Enma would revive the Simon and Hibari would regret siding with the Vongola. Hibari responds that he isn't on either side but does as he pleases, which Adelheid claims makes him a true cloud of the great sky. While Hibari doesn't like her phrasing, he states that the sky does allow the clouds to move freely, but one day he would bite up the sky itself. After Demon possesses Mukuro's body, Hibari challenges him to a one-on-one battle and tells Tsuna and the others not to interfere. At first, he is seen gaining the upper hand until Demon copied Ryohei's Vongola Gear and uses Maximum Sunshine Counter. Hibari is able to dodges this since Demon let it miss on purpose and then traps Hibari into his Illusionary world like he did to Gokudera, Yamamoto, Lambo, and Julie. After Tsuna defeated Demon, Hibari exits the world and sees the final key. A week later, Hibari leaves to fight the recently released Mukuro. (Unfortunately, in volume 36 side picture, Mukuro is not present since he already left for Jura).
Arcobaleno Request Edit
Reborn asks Hibari if he wanted to be a part of the Representative Battle of the Rainbow; Hibari declined Reborn's request. Reborn states that Hibari got a severe case of hives after being with Tsuna and his Guardians during the long battle with Demon.
1st Day of Representative Battle of the Rainbow Edit
Later, it is revealed that he became Fon's representative, during the first battle royale round, where he eliminates Ryohei, but is immobilized by Yamamoto's Rain Flame Tranquility characteristic, which allowed Yamamoto and Gokudera to escape.
2nd Day of Representative Battle of the Rainbow Edit
On the second day, before the battle started, Hibari revealed to Dino that his sole reason for becoming Fon's representative was to 'bite him to death'. Later, Hibari, along with Fon, fights Team Mammon. Before he could finish his battle with Xanxus, however, the watch announced that the battle is over. Hibari, cannot accepting the result and still want to fight, destroys his own Boss Watch and thus eliminates Team Fon from the Representative Battle. Since Xanxus was stopped by other Varia members from continuing their fight and destroying the boss watch, Hibari turns his attention to Dino.
Grand Convention Edit
It revealed that Hibari had been fighting Dino since the end of the second day battle at Namimori Mountain until Tsuna arrived and revealed everything about Arcobaleno and the Representative war, shocking both of them. Later, he, along with people who Tsuna had contacted yesterday night gathered at Tsuna's house as Tsuna asked for them to fight together.
4th Day of Representative Battle of the Rainbow Edit
At the fourth day and last day of Representative Battle of the Rainbow, Hibari is chosen as one elite members to fight against Bermuda and his team. He saved Dino from Jaeger's attack and work together with Mukuro to fight Jaeger's formidable strength. He was confident when Jaeger was unable to short warp his weapon, but this proven to be wrong when Jaeger short warp and appear behind Hibari, dodging Hibari's Vongola Gear. Tsuna arrived in time to save him from Jaeger's sneak attack. He and Mukuro protected Tsuna as Jaeger continued his attack, which Jaeger responded by stabbing them through their shoulders. Mukuro used his illusions to keep Jaeger in place as Tsuna shot his X-Burner at him, defeating the Vindice. However, this leaves Hibari and Mukuro gravely injured and they collapsed, unable to continue fighting. Bermuda interfered before Tsuna could destroy the boss watch. He destroyed Hibari's and the other remaining members' battler watches to prevent them from assisting Tsuna.
After Tsuna defeated Bermuda and Kawahira removed the Arcobaleno curse, he was submitted into Namimori Hospital along with Dino, Basil, Varia, Byakuran, and Kokuyo Junior High Gang. Because of Xanxus' attack, the wall of his room was destroyed, disturbing his sleep. This annoyed him and he counter the attack with his tonfa and enter Xanxus' room as he said that he will bite those who disturb his sleep to death with several Hibirds flying around him, making Tsuna wonder how Hibari was able to sleep with all those Hibird chirping. His tonfa caused the wall that connected to Mukuro's room destroyed, startling Mukuro and his subordinates who were eating their snacks. Since their rooms are all connected, Reborn suggested to having a pillow fight, which they replied by suggesting another games that will cause more injuries, destroying some parts of the hospital. In the final chapter, he is shown when Tsuna narrates his thought of how he has friends that he could rely on now.