He is the son of the Cavallone Nono. As a teenager, Dino attended a school for children of the mafia, where he first met Squalo. Reborn tutored him before leaving for Japan.
Dino is introduced in this arc, having snowball fights and friendly competitions with Tsuna's Family, carrying out tests for Tsuna's chosen Guardians to see if they were worthy, and generally just hanging out with Tsuna's Family.
Dino becomes Hibari's home tutor in order to train the latter for the Ring Battle. Thus, Dino travels with Hibari around the country in order to train him in various environments, with his right-hand man Romario, (because Dino will most likely mess up without Romario's presence.) He has a little difficulty in training Hibari, since Hibari just wants to "bite him to death." Dino sees Hibari as being quite strong for his age, which is the reason why he is needed for Tsuna's Family.
Dino later appears after when Byakuran announce his official battle between the Vongola and the Milliefiore Famiglia, in a battle of Choice. Dino meets with Hibari on the rooftop of Namimori Middle School, where Tsuna and the rest were taking a break from training, promising to train Hibari in the upcoming battles. After his trainig with Hibari, Dino comes to check on Tsuna and the others on their training. But however he alone sees that Tsuna's Box Weapon attacks him, Takeshi Yamamoto and Basil. Basil and Yamamoto together were able to seal the Box Weapon back to its box. Dino tells Tsuna his Box Weapon attacked him because he opened it incorrectly, and if he does it again, he'll break it for good.
Dino assigns everyone to new tutors for the time being. Ryohei Sasagawa and Lambo under Hayato Gokudera, and Chrome Dokuro under Bianchi with I-Pin helping out. He tells Tsuna that he'll have to practice on his own, and Yamamoto the same because if he teaches him anything wrong, he will be "sent flying" by "that guy", later revealed to be Superbia Squalo.
Dino reappears during the selection of the teams, right when Hibari says that he doesn't care about the rules. He tells them that he snuck right in when they were being transported to the Lightning Field. Dino manages to convince him that he should wait to attack, because after the battle, he can fight anyone he chooses. As the end of Choice draws near, Shoichi Irie mobilizes the base in an attempt to escape from Kikyo. After a long chase scene. Kikyo manages to destroy the base and inflict a fatal wound on Shoichi. The Cervello arrive, and tell Tsuna that they need to check Shoichi's target marker, in order to see who's the winner. But Yamamoto tells everyone that he too, has defeated the target. This shocks everyone, but Kikyo however replies that they're too quick to judge, as Deisy is still alive. Because of this, the Cervello declare the Millefiore Famiglia the winner, but Shoichi reinsures everyone that he can still fight. Dino and the rest of co. arrive to help treat his injuries, as he tells everyone the story between him and Byakuran. He than tells everyone that Byakuran has the ability to share his knowledge arcoss multi parallel worlds. Byakuran congrulates them for understanding so much in so little time, but then demands Tsuna to give the Vongola rings to him.
Shoichi then reminds Byakuran of their past battle of Choice, in which Byakuran lost and agreed to give anything in return on their next battle of Choice. Byakuran denies this, but Uni suddenly appears and says that she also know about this, and that Byakuran should give the Vongola a rematch. Byakuran denies this once again, in which Uni tells him that she will no longer be a part of the Millefiore Famiglia and asks Tsuna to protect her from Byakuran. Dino suggests to Tsuna to reorganize themselves as he observes that Byakuran will make the battle last long. As Byakuran catches up to them, Dino volunteers to stay and buy some time for the whole Vongola family to escape. He also seems to have information as to Mukuro's whereabouts since he commented that Mukuro will be helping him soon just before the real Mukuro appeared.
After Tsuna and his family returned to Namimori, Dino can be seen with Hibari running off to fight one of the Six Funeral Wreaths that landed at Namimori School. There they fight Deisy and defeat Deisy's Box Weapon, the Sun Rhino, with little difficulty. Deisy states that he was only going easy on them because he was happy that he found them, Deisy then reveals a box embedded in his body and activates it, changing his body into a weapon. Dino then releases his fully powered Sky Horse, with flaming wings that gives it an appearance of a Pegasus, which is then defeated by Deisy's left arm after the Sky Horse removed it. Dino then unleashes his ultimate technique, but to his surprise Deisy knows the technique, which Dino suspects from Byakuran's ability, and dodges it and incapacitates him, Hibari then comes to the rescue smashing Deisy through the school, and kicking Dino to Romario, stating that they need to stop going wild in the school. Dino then states how Hibari reminds him of the First Vongola Cloud Guardian and Hibari shows his Vongola Hedgehog's Cambio Forma.
At the ceremony, Dino greets Tsuna and says that he was proud of him, and also mentioned that he received the memories of the battles in the future from Uni. He mentions that he was able to see through Chrome's illusion of Yamamoto and questioned Tsuna about it while also offering their help. He is later seen when Timoteo was passing down the Vongola Sin down to Tsuna, when suddenly a loud noise sounded, followed by an explosion. Dino told Romario to protect the guests. Later, it was revealed that the true culprits were the Simon Famiglia. Enma easily overpowered Tsuna and his Guardians, but when the Varia and Dino try to help, they were stopped by Adelheid Suzuki. A shocked Dino was seen after Enma defeated Tsuna.
Dino is seen at Tsuna's house, listening to Reborn's explanation on why he wanted them to fight for him, and, after agreeing, the curse of the Arcobaleno. Afterwards, he leaves to go to his hotel, running into the Varia along the way, noticing Mammon along with them. Romario then pulls him up and informs him that the Varia were staying in the same hotel as them, much to his shock. Later, Dino greets Tsuna and Reborn as they arrive at the hotel, getting nervous as they asked him if there were other Arcobaleno representatives. Belphegor then swings in and drags Tsuna to the Varia's room. When Dino finally catches up to them, a man named Wonomichi bursts through the floor and announces himself as the planner of the "Representative Battle of the Rainbow" and that he would be explaining it.
Later, he and Reborn mutually agree that Tsuna should be their Representative Boss, and leaves to try to convince Hibari to join their team. After the first day of the battle ends, he apologizes for not getting Hibari to join, and that the latter had told him he would give his answer on the first day of the battle. He wants to be a part of the second day of the battle, so Reborn makes arrangements for him to become Tsuna's class's English teacher.
Later, during the battle between Team Fon and Team Mammon, Dino watches and reports to Reborn about the situation. A while later, just before Xanxus's shot from his X-Guns hit Hibari's Boss Watch, Dino shows up and deflects Xanxus's shot with his bullwhip, saving Hibari. When Hibari says that he wants to fight Xanxus alone, Dino deliberately provokes Xanxus by bringing up his match with Tsuna. As Xanxus mercilessly assaults Hibari, Dino suggests that Hibari should try to break Xanxus's watch through a slight opening. Hibari takes his advice, managing to dodge Xanxus's attack, but unable to break his watch.
Dino is last seen with Romario and Enzo when Tsuna thinks about the people he (Tsuna) can rely on.