Ninja to Gokudou

Shinoha is a frickin' NINJA. He can't even smile because of a dark trauma in his past that you'll find out about later. But for now, what you need to know is, he kicks ass and can kill so many guys. Kiwami, on the other hand, looks like a regular business guy, but actually he's a flipping YAKUZA. Everyone knows ninjas and yakuzas have been at war for three hundred years, so when Kiwami and Shinoha meet, it's like, fwoosh, slice, kabloop, stab stab stab... My point is, this manga has REAL ULTIMATE POWER and, if you read it? Maybe you can too.

(Source: Kodansha USA)