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A character from Getsuyoubi no Tawawa. 理系 in her name means "science"; she has also been called 講義アシスタント / Kougi Ashisutanto (Lecture Assistant) and 家庭教師 / Katei Kyoushi (Home Tutor) in earlier appearances.
As indicated by her name, she is a teaching assistant in the subject of chemistry, and worked as a part-time science tutor to an unnamed student when he was trying to pass his college entrance exams. She's also an old college friend of Kouhai-chan.
She has short, dark, messy hair, and like many female Tawawa characters, she has large breasts.