The Black Company

(from ebookjapan):

The world's dumbest gang, that's right, "The Black Company". Consisting of the leader of the gang, Kato Koneko, a.k.a. Capone, is the "biggest" gangster in the world. Taro, with his fat belly button and heart. And Jiro, who has a scar across his face.

They are three goofball gangsters who have never once succeeded in a mission, but for some reason, they are relentlessly pursued by the Oni detective Higetora.

"Dang it, you'll see, I'm going to succeed in my mission today!"