While Haruka is the oldest one in the bunch, it doesn't mean she's the most mature one. She often acts like a drama queen and when she's intoxicated, she gets very rowdy and lecherous.

She's currently studying bio-chemistry in college. Despite being wasted most of the time, it seems she puts at least some effort into her work and into her studies. She often likes to ferment alcohol in school, trying new techniques. Sometimes she brings home her projects for the older girls to try out.

She likes to harass Saki and Kana, especially when she had a drink or two too much. (She's always in for a drink, and has a preference for sake.) Haruka has a gigantic fetish for anything cute. She often gets very excited when it comes to thinking of girls having a clichéd moe appeal to them (such as seeing Kana in a school swim suit and calling Mika a "loli" because she's short and flat-chested).