|Name in Japanese||委員長|
|Voice Actor (Japanese)||Noriko Rikimaru|
|Voice Actor (English)||Kate Bristol|
Iina is an average sized girl who has green hair and eyes. She wears Glasses and is seen mostly wearing her Isono Junior High school uniform. It is shown when she takes off her glasses that she is extremely beautiful, even making Nagasumi blush.
Despite the fact that she is the class president, her presence is usually too passive to be noticeable.
She later reveals that she has very strong feelings for Nagasumi. Later, Iina writes a love letter to Nagasumi, to confess her love, but accidentally confesses to Sun due to not looking at the person she was confessing to. This event leads to the sudden creation of an alternate persona, the "Last Amazoness", a girl-loving warrior who declares her intent to have Sun as her own. Iina uses this persona when she's trying to get noticed or when she needs extra confidence. In recent volumes of the manga, the "Last Amazoness" takes an active role in fighting troublemakers after receiving a gender-reversing mermaid weapon, "Gender-X", from Surtan. Iina also works with Maki on occasion, believing her to be a fairy, her desire is for people to find out her real name. Her actual name was revealed only at the last page of the last volume of the manga by Mawari as "Iina Chiyo", ending the manga with her cry of victory as someone finally calls out her name.