As one of the world's "I Prescelti Sette" (Strongest Seven), Fon was selected to become one of the Arcobaleno. After his transformation, he began teaching I-Pin, a young female Chinese assassin.
Reborn states that Fon was the champion of the top martial arts, and that his name means "Wind" or 風. His Trial was of leadership qualities. Tsuna, Haru and Lambo had to catch him within an hour; however, Fon was extremely agile, and was therefore able to avoid them for most of the time during his Trial. Fon had wanted to teach them that to catch wind, they would have to wait for its arrival, and not force it to go anywhere, as it would run away.
Afterwards, Tsuna arranged a plan to catch Fon. Lambo would try to corner Fon into the art room. Haru would then hide there and scare him. With Lambo blocking of the exit and Haru inside the room, Fon's only way out was a door on the left. However, Tsuna was waiting there. When Tsuna was about to catch him, Hibari arrived and so Fon was able to escape. I-Pin, who was hiding in the shadows since the beginning of the match, intervened and prevented Fon's escape. They both matched each other's moves using martial arts and Gyoza Kempo. However, I-Pin used Gyoza Kempo on Lambo and used him to send Fon flying into Tsuna's lap, where he had been beaten up by Hibari. This then concluded the Trial of Leadership. He later stops Verde's Pawn Missile from capturing Lambo and enters the battle against Verde, he is captured along with the other Arcobaleno after being weakened. However it is revealed that it was actually an Illusion and Fon was safe, but immobilized. He helped Hibari take down the Cloud Lobster.
After he, the rest of the Arcobaleno, and the Vongola Guardians, take down Verde and escape the sinking island, Fon tells I-Pin that he is returning to China.
Fon is called, along with the other Arcobaleno, to train Tsuna and the others. He is paired with Gokudera, since they both share the Storm Flame. He started to tutor Gokudera by observing him, in order to learn about Gokudera's personality.
Later, during G's Trial, he bought him some time to distract Gokudera while G disguised himself as Gokudera to test Tsuna and Gokudera's relationship as Boss and right-hand-man.
Fon and the rest of the Arcobaleno are revived by Uni after the defeat of Byakuran. This is the first time Fon was shown in the manga. Together with the rest of the Arcobaleno, he sealed the Mare Rings.
He and the other Arcobaleno (with exception of Aria and Lal) experienced the same dream and met the man with the iron hat, the one responsible for bringing the World's Strongest "I Prescelti Sette" together, who became the Arcobaleno as a result. The man with the iron hat asks them if they wanted to be freed from Arcobaleno curse, to which Fon quietly replied in the positive, later going with Reborn's protest that they couldn't trust the man with the iron hat, but relenting when the man with the iron hat threatened to never appear before them again.
Afterwards, he was seen standing on a lamp post as he wondering who he could ask a favor for. He is then seen on another lamp post watching Skull requesting the Simon Famiglia transfer students' help, commenting that the Flames of the Earth would be difficult to fight against.
When Wonomichi, the messenger of the man with the iron hat and the planner of the Representative Battle of the Rainbow, explained the rules of the Representative Battle of The Rainbow to Fon, Fon assured Lichi that he had found someone that he could ask to be his representative.
Later, at the start of the battle when Tsuna's Guardians are rushing over to see what happened at an explosion, they are stopped by Hibari, with Fon sitting atop his head, revealing that Hibari is Fon's representative.
On the second day of the Representative Battle, he is seen with Hibari going to the hotel where Dino is staying, and when getting out of the elevator they encounter the Varia. Fon removes his curse and defeats 3 of the Varia quickly, with Hibari asking why he was doing something unnecessary, to which Fon responded that he didn't want to see Hibari face the Varia alone.