21-year-old Shinomiya Yuki has no friends and spends his days alone working part-time jobs. One day, when he returns home as usual after a night shift, a male stranger who has been stabbed in the abdomen with a knife is sitting in his room. The man wakes up at the hospital that he has been taken to and identifies himself as Shinomiya Yuki to detectives. Then he points to Yuki and states that he stabbed him. Yuki flees the hospital right away and becomes a fugitive in an instant. At that moment, a mysterious woman called Zoka appears right before Yuki and asks him to help her take revenge on her father’s killer. He decides to collaborate with her. Zoka is a “leech” who goes from one house to another while its occupants are away. The two of them eventually encounter Kara, a legendary leech who lives like an empty shell solely for the purpose of revenge.

Set in the future where it is commonplace for high tech crimes to get through cyber defense, Iwase Shobei, a wealthy man and well-known collector of gems, asks private investigator Akechi Kogoro to provide personal protection for his daughter Sanae. Iwase has been warned that she will be kidnapped. The mysterious phantom thief Kurotokage, who deftly replaces precious gems with imitations, stands in Akechi's way. However, Kogoro catches on that Madam Midorikawa, the owner of an exclusive hotel who has give shelter to Sanae, is actually Kurotokage, and prevents Sanae's abduction. However, he is hampered by a trick laid in the entire hotel and fails to catch her. At that moment, the thief and famous investigator secretly fall in love. Akechi chases Kurotokage and eventually learns about her tragic past and surprising identity. Although swayed by forbidden love, both have a final showdown at Kurotokage's secret museum which houses her collection. Who will be the victor?—Jdrama Weblog

A young couple's announcement of their engagement to their friends is followed by a series of interactions and conflicts that forces everyone to reflect on their lives.