Yataro Sarumaru, nicknamed "Saru" is an average high school boy who daydreams about idols but otherwise has no luck with girls. While working with his father, a locksmith in Asakusa, Tokyo, he has gained exceptional skills to pick just about any lock. Using his exceptional skills, Yataro then finds himself solving various mysterious cases, while also trying his luck with the girls.

Romeo, A.K.A. Kosuke Matsuyama, is a second-year high school student. A nice, normal, nonviolent type, he suddenly finds himself in the middle of a rampaging crowd of Korean boys, outraged by insults perpetrated by several of his idiotic class-mates on two Korean girls. He makes a narrow escape, but soon after, he and his best bud Yoshio are sent by their home-room teacher to invite the Korean students to a friendly soccer game as a way of restoring the peace.