From Impossibility:
Morisawa Kai and Sato Tatsuki are best friends. However, unlike Kai, Tatsuki is completely unreliable, lazy and ill-tempered. One day Tatsuki takes Kai out driving in his new motocycle only to get into a bad accident that leaves Kai dead. However, Kai’s spirit ends up in a body of a girl named Fujii Marika. After seeing how cold and unaffected Tatsuki as well as everyone else was after his death, Kai transfers to his previous school in which he starts noticing flaws to Tatsuki’s cool mask...