Tenchuuin Seika

Ai's sister-in-law. (Ai's husband's sister) She is a gorgeous wife of a wealthy family. She feels her life's purpose is to improve her own body. She also understands the value of her body and married into the Tenchuuin family five years ago as an instrument of a political marriage for the development of the Narushima Group. The difference in age between her and her husband is over 40 years.

However, she is actually the daughter of a concubine and not a legitimate daughter of the Narushima family. This is a top secret known only to a few people in the Narushima family. Because of this, she had to go through a lot of hardships when she was a child. Therefore, she may appear to be a carefree hedonist, but in fact she is extremely smart and has a great deal of insight.