Yataro Sarumaru, nicknamed Saru, is an ace in the locksmith trade and is obsessed with girls. This (almost) average teenager is given a hardly ordinary mission which marks the beginning of his adventures!

The story follows Yatarō "Saru" Sarumaru, an ordinary high school boy who daydreams about idols but otherwise has no luck with girls. However, this silver-haired son of a locksmith also happens to be a lock...