Kanta Komori is the legitimate successor to "Hotto Surussho," a technique for causing mischief. He fails to pull a prank in a train properly and is chased by the mafia. He runs over a girl on his motorcycle while trying to escape from them. Konatsu Yumemura loses her eyesight because of the accident. Kanta realizes that it is his fault, so he seals up his mischievous techniques and starts to help her commute back and forth to the hospital.

A few years later, an assassin from the archrival "Nanto" murders his uncle. On his deathbed, he tells our hero that Konatsu's eyesight can be restored through secret techniques of Hotto. Our hero unseals the techniques to bring back her sight...

[From gamelexgs]