Jagaaaaaan

Jagaaaaaan (ジャガーン) is a manga written by Muneyuki Kaneshiro and illustrated by Kensuke Nishida. It is serialized in Shogakukan.

Plot
Shintarou Jagasaki, who is a neighborhood police officer, lives with his girlfriend while working a job that is killing him slowly with annoyance. It looks like he will end up marrying soon and live a boring life with a nuclear family - a grim future for a guy with dreams! One such day, a mysterious monster appeared on the train and he suddenly can shoot with his right hand like Master Buppanatsu, the eggplant mascot of his city!