Ren Mikihara serves as Secretary of Jindai High's Student Council and is close friends with Kaname. She's also the daughter of a yakuza boss, though you wouldn't know it to look at her—she embodies the Yamato Nadeshiko ideal, known for being beautiful, reliable, and genuinely caring toward others.
There's definitely something going on between her and Atsunobu Hayashimizu, the Student Council president, though she keeps that pretty close to the chest. Beyond the surface, though, a lot about Ren remains mysterious.
Kaname has taken to calling her "Oren-san" as a personal preference. The name Ren itself breaks from an old Tokugawa-era naming convention where women typically had two-syllable names, often with the honorific "O-" prefix attached. It's a small detail, but it's the kind of thing Kaname clearly cares about.
Content compiled by AnimeList.moe from publicly available sources.