Age: 12
Birthday: October 1st (Libra)
Chiyo is a first-year student at Ohananomitsu Middle School and Rentarou's cousin. She's also her class's president, a role that suits her perfectly—she's naturally organized and reliable, someone who can't stand mess, rule-breaking, or anything even remotely untidy. The moment she spots something out of place, she has to fix it immediately. She's strict about the little things too: no rudeness, no messy rooms, no porn magazines lying around, absolutely no underage smoking. Basically, if it's against the rules or looks bad, she's against it.
There's one weird quirk though: take her glasses off and she completely falls apart. She gets incredibly anxious and breaks down crying. It's a pretty dramatic transformation.
The name stuff is kind of clever in Japanese. "Chiyo" uses the characters for wisdom and participation, and when written in hiragana as いいんちよ, it basically mirrors the second half of 学級委員長 (the full term for "class president"). Her birthday being October 1st is also a thing—Japan calls it "Glasses Day" because the numbers 1001 look like a pair of glasses when you squint at them. So yeah, fitting for someone who can't function without hers.
Content compiled by AnimeList.moe from publicly available sources.