Motoko Aoyama is a high school student who was trained to be a skilled user of the sword in the style of Shimei-ryu.
She is unusually tall for her age being the tallest Hinata-sou resident at 173 cm ('5'8"), even beating out Keitaro.
She has a hatred for men that stems from her older sister's marriage. Motoko is also afraid of turtles and tends to panic enough where she'll attack with her sword to drive away hot springs turtle.
Believing that her sister Tsuruko Aoyama became weak from falling in love, Motoko moved to the Hinata-sou to distance herself from her sister. However, Keitaro Urashima's arrival proves to be a thorn in Motoko's side as she believes him to be a threat to her calm and concentration.