Birthday: November 7
Weight: 38.40 KG (OVA 7)
Height: 145 cm (OVA 7)

Ako is the elder twin sister. A way to tell her apart from Riko is that she wears a hair clip to keep the hair off her forehead. She has a reliable, level-headed personality, but can be sullen, moody, even a bit childish and is quickly embarrassed. She carries herself differently than her sister, is more skilled in cooking which she learned to help her mom out with the housework, and is strong with alcohol which she sometimes uses to her advantage to knock out Riko to have the livelier Keita all to herself. She is a closet pervert and more often planning her seduction of Keita, even hiding porn magazines in her room. At school, she is on the school committee, but has a habit of abusing her authority to get Keita.