A bloodcurdling scream rings out from a warehouse in a bayside district. Flames flicker, reflected in a pair of eyes. A shoe clatters across the ground. The whoosh of fire mixes with the wind. Gazing into the fire is Kayoko Hasumi, an investigator from the all-female Hasumi Detective Agency, and her German Shepherd ex-police dog, Masa, who can understand human speech. The heart-wrenching event that befalls them next serves as the drama’s prologue. 7 years ago, Kayoko’s father, a career newspaperman in the society section committed suicide. But the facts of the suicide remain shrouded in mystery. Kayoko’s mother, Kyoko, has been secretly and singlehandedly investigating her husband’s death ever since… until a certain incident threatens to bring Kayoko and others into the mix, and closer to the truth.

Just where is Level 7 and what is it? Two completely distinct plot lines ultimately cross paths and converge on a heinous murder. A man and woman wake up in a condominium room but have no memory of anything. The only clue they have to their identity is a tattoo on their arms that reads, "Level 7." Meanwhile, in a separate location, a solitary elderly lady goes missing having left the message, "Once you arrive at Level 7, there is no return," prompting her granddaughter to begin a search for her whereabouts.

Miko, who abandons her ascetic training to become a convent nun to instead assume the singing dreams of her twin brother’, Mio, by replacing him as a member of the hugely popular rock band, A.N. JELL. The band’s leader, Ren, though overflowing with musical talent, is also an extreme neat freak and perfectionist who keeps others at a distance and refuses to recognize Miko or anybody else’s talent.
The band’s other members consist of Shu, who seems to have a little more of a forgiving personality, but is actually just extremely detached. Yuuki, while on the surface a complete airhead, keeps balance in the band, particularly between Ren and Shu. Miko leaves the communal life of a nunnery to join that of a rock band, but will she be able to “gel” with A.N.JELL? And bringing a girl into an all-boy band is sure to produce some interesting chemical reactions; perhaps even some chemistry between Miko and Ren, not to mention a fair share of jealousy, tears, camaraderie and even a search for parental love.