Tomoko is a native of Kobe and speaks the Kansai dialect. She has a very serious, responsible nature, and serves as the class president. Her seriousness is conveyed by her tightly bound hair and coke-bottle glasses, though she is quite pretty when she removes these features (in fact, the change is so drastic that in To Heart: Remember My Memories Hiroyuki and company don't recognize her at all when they encounter her in Kobe, until she puts on her glasses and holds her hair in a ponytail). It is hinted that she might have liked Hiroyuki in To Heart: Remember My Memories as she said he was slow when he asked her why did she tell him about her family's past.
She moved from Kobe as a result of problems between her parents. Her quiet and concentrated nature is one of her ways of hiding her problems and she will often keep to herself.