She works in the accounting department and gets pulled into A-TEC's orbit when Nagisa tasks her with straightening out the class's finances during a rough patch. When things get tight enough that the class has to relocate back to their original factory setup, she's essentially forced to take the job seriously. On top of managing the books, Nagisa also has her keep tabs on Yuji for reasons that remain his business.
Her real name is Hanako Hattori—a fact she really doesn't enjoy having brought up. There's something about it that clearly gets under her skin whenever it comes out. Despite the awkward arrangement and added responsibilities, she seems to have developed genuine feelings for Nagisa, though she'd probably rather keep that under wraps.
Content compiled by AnimeList.moe from publicly available sources.