Jimeko's one of Kohina's classmates, and she's got that classic "shy tsundere" thing going on. She's constantly trying to provoke Kohina—hoping to get some kind of reaction out of her—but Kohina pretty much always blows her off. It's become kind of her thing, really: putting in all this effort to antagonize someone who doesn't really care to engage.
Content compiled by AnimeList.moe from publicly available sources.