Majo no Inu

"Then hire me. For a price..." Natsumi Iida, who runs an anything-and-everything shop specializing in rough-and-tumble affairs, is always looking for stimulation, and spends his days in boredom. Then he meets a mysterious young man, Keigo Asakura, who is being chased by creepy men who will not die even if he shoots them with a gun. Intrigued by Keigo and his environment, Natsumi attempts to contact him, but...?

(Source: Kaiohsha, translated)