Relax, I'm A Ninja

A Clan of ninjas in San Francisco may sound improbable—but as the son of
a ninja master, Tosh Ito knows what lurks in the shadows of his city.
Or at least he thought he did.When a killer with a
poisoned blade starts cutting down teens, Tosh enlists Amy Sato—newest
ninja recruit and his best friend’s crush—and sets out to uncover the
killer's identity. What they find is ninjutsu more evil than they could
have ever imagined.As Amy and Tosh grow closer, they
discover their connection unleashes a legendary power that could stop
the murders. Problem is, that power may be exactly what the killer is
looking for, and wielding it could cost them both their souls.