Dragon Ball: That Time I Got Reincarnated as Yamcha! (manga)

A Japanese high school student is on his way to a Dragon Ball event and makes a detour to hit on a cute girl. Unfortunately, he meets with an unfortunate and fatal accident before he reaches her and, to his great surprise, wakes up in the Dragon Ball universe as Yamcha! Being a Dragon Ball fan, he knows exactly what misery awaits him as Yamcha, so he takes matters into his own hands and vows to make Yamcha the strongest Dragon Ball character ever!