- "While being with your girl may be good, keeping Sin away from her is better."
- —Luzzu, quoting Chappu to Lulu and Wakka
According to Wakka, Tidus looks a lot like Chappu, which is why he had such an easy time bonding with him. Lulu was initially annoyed by this, because of her intimate relationship with Chappu. Chappu can be seen on the Farplane appearing before Wakka and, later on, Lulu as well. If looked at closely, it can be noticed that Chappu looks very similar to Tidus, other than the hair color and style.
He was raised in Besaid Island alongside his brother Wakka after their parents died. Chappu was at a very young age so Wakka took care of him and tried to act more as a father than a brother. Both eventually met Lulu and Yuna when they arrived to Besaid Island. At some time Chappu and Lulu began a relationship together before the events of Final Fantasy X.
Wakka gave him a sword, but Chappu would prefer to fight with an Al Bhed machina (which is the reason why Wakka came to resent them on a personal level). Chappu was a good friend of Luzzu as he was the one who convinced him to enlist in the Crusaders and also to be able to protect his girl from Sin. When Wakka and Lulu found out about it from Luzzu, they both hit him hard. Chappu said that once the Aurochs won the cup, he would propose to Lulu.
While not much is known about his death, it is known that he died somewhere near Djose, due to the fact that his body was crushed and left on the shore there. He died fighting Sin to keep Lulu safe, using an Al Bhed machina weapon.
- "Knock it off with the surrogate parent thing and give us both a break. I just need you to be my brother."
Wakka remembers that as a kid, Chappu told him about a sphere that showed their parents and nervous about his future role as a father, he goes looking for it. After the Gullwings helped him, he found a sphere, but not the one he was looking for. Instead, it showed various (and apparently random) locations on Besaid Island. Wakka later decided he did not want to see the sphere anyway, preferring the image of his parents he had in his head.
Chappu later appears in a sphere given to Wakka, from the Gullwings which was given to them by Beclem, who was Chappu's war buddy. The sphere shows Chappu talking to Wakka about the sphere of their parents he found and told him he made the whole thing up. He also told him of the days they spent as brothers and how Wakka always tries to be a parent to him. Chappu wanted him to stop acting like a parent and just be his brother.