Miho is Yutaka's rival. She is the host of the radio show Pon de Night. She used to be a softball player aiming for the Olympics but she got injured, and decided to become an idol instead due to her schoolmate's urging. It was later revealed that she is N.02 fan of Horiuchi, Yutaka.
Sui is Kei's younger brother and resembles a younger version of Kei. Initially, he dislikes Kei because he finds living with him disgusting and thinks of him as a robot wearing human skin. Because Sui feels very inferior to his brother, who is good at everything, he believes that he cannot reach Kei's level and he refuses to take his studies seriously. However, when he sees that even his "perfect" brother can become desperate and caring, Sui develops a huge brother complex. Sui likes to call Hikari "Stupid Girl", but approaches her frequently when he thinks that Kei needs help. He is in grade 6, class B at Hakusenkan's elementary school division.
Sakura is the daughter of the head of Ushikubo Medical Manufacturing Group and is Kei's first marriage meeting (or omiai) partner to appear in the series. While she does not consider Kei her type, describing him as a "dark lord" rather than a "prince", she considers him a possible marriage partner because his abilities would be advantageous to her family's business. Sakura hates dishonest people with a passion, and her family's motto is centered around honesty and punishing/loathing dishonest people. Hikari's straightforward and honest nature allows the girls to become friends. She attends the same school Yahiro does and sometimes plans stuff out with him (whether the plans be good or evil). Sakura falls in love with Jun at first sight, as he fit her ideal of someone who was a "prince", and accepts his split personality. She begins to date Jun soon after; however, because of her forceful personality, she is uncertain if Jun reciprocates her feelings until he admits to her that he does. Sakura first appears in volume 4.
Sayaka is the older sister of Yutaka. She was once a member of eight clubs, and is quite popular (and legendary).
Tsutomu is an eccentric songwriter for idols, used to be known as the Master of Pop. He is a self-proclaimed lolicon.