Teshigawara Saki is a high school girl who lives in Roppongi with her perverted father and grandfather. Though she may seem like an ordinary girl, she has the extraordinary ability to open any kind of lock. Saki uses this ability for whoever asks, regardless of whether they are the police or yakuza. But with the organized crime situation worsening in Roppongi, this openness may end up getting Saki more involved than she would like...

(Source: MangaHelpers)