|School||Toumei High School|
|Occupation||High School Student|
|Anime Debut||Episode 3|
Aiko has long and sleek auburn-brown hair that falls to the middle of her back. She also has dark brown eyes, smaller than any other female character in the series. Aiko is noticeably taller than Mei. She has a slim and athletic figure which she obtained through excessive dieting. She is shown to have stretch marks on her stomach as a result.
Aiko is seen wearing five earrings: two red studs on her right ear and three silver hoops on her left.
In years prior to when the anime takes place, Aiko had noticeable acne and was roughly 40 pounds heavier. Seeking to satisfy her boyfriend(s), she began dieting and became self-conscious about her skin, purchasing and wearing an assortment of beauty products in an attempt to cover her imperfections. Much to her dismay, the products only worsened her complexion.
At that time, Aiko had curly locks held back with a black headband.
While being straightforward and bold, Aiko is a very helpful and caring friend. However, she can be harsh to those who threaten her interests or hurt the ones she cares for. The latter is noticeable when Aiko notifies Yamato that he is hurting Mei by secretly spending time with Megumi Kitigawa.
Yamato was there for Aiko in her time of need when she felt insecure about her acne and her weight. Aiko, feeling desperate and lonely, pleaded with Yamato to sleep with her. Yamato hesitantly agrees, feeling that this was her last resort to restore her confidence. Aiko deems Yamato her 'first love' as a result. Prior to dieting, Aiko dated many boys, perhaps trying to fill the lonely void in her heart. Though her popularity increased when she was beautifying herself and dieting, her many relationships ended badly, often with her boyfriend having cheated on her.
After Yamato compliments Aiko's natural looks, she becomes drawn to him, as Yamato was the first person to ever do so. She falls in love with Yamato after realizing that he was the only boy at the time who truly cared for her.
Aiko immediately disliked Mei after seeing how seriously Yamato likes her. She becomes frustrated due to the attention Mei receives from Yamato, believing herself to be deserving of Yamato and closer to him due to their history.
After being bullied by a boy at school regarding her history of dieting, Aiko notices Mei standing up for her. After she realizes the pain Yamato's relationship with Megumi Kitagawa is causing Mei, she begins to soften and become a better friend.
The two girls are good friends. They were deciding a gift for Yamato and Mei's anniversary, and when Megumi told Asami to go to the fashion show, she raised her voice and Aiko became upset when Megumi yelled at Asami.
For relationships prior to when the anime takes place, see History.
After getting over Mei and Yamato's relationship, Aiko is good friends with them both.