رین ایبا

Birthplace: Tokyo

Three sizes: Growing → B86/W56/H87

Itsuki's younger sister and Yuzuki's step sister, who is a year older than her. She is quite fond of her older brother and is irritated by Yuzuki, saying that she acts nice just for attention. She is also known to tell lies in order to make Yuzuki upset. She is mischievous and loves to cause trouble. She shows a slight interest in Haruto.

[Spoiler: After the one year time-skip, she and Yuzuki have grown closer. She tries, and succeeds, in getting Haruto to realize his lingering feelings for Yuzuki while he was still dating Asuka. In chapter 202 she finds out that Haruto and Yuzuki have finally slept together after a dating for a year and she soon realizes that she really does love Haruto. She denies this, however, stating that she just feels left out now, though she later reassures herself that just because they slept together doesn't mean they'll be together forever, implying that she won't give up.]