She has long brown hair and black eyes. Her hairstyle is almost the same as Tsukasa Ayatsuji. She wears the formal school uniform but she wears a vest instead of a black coat.
She is a shy girl and has been in love with Junichi ever since grade school. She has been secretly stalking him and is very overprotective of him, leading her to break other girls' hearts for what she thinks will save Tachibana from another heartbreak. She may be an example of a Yandere.
Risa appears in Episode 25 of the first season. She confesses her love to Junichi, which he later accepts and agrees to become her boyfriend, but she wants to keep their relationship a secret. Junichi wants to go the Founder's Festival with Risa and introduce her to his friends, which Risa thinks about it. Unknown to him, Risa's unwillingness to come is because at the time when he was getting close with Haruka, Kaoru, Sae, Ai, Rihoko and Tsukasa, she was stalking him and prevented the girls from falling in love with him by showing them a doctored photo that Junichi already has a girlfriend.
Later, while visiting the park where he was stood up two years ago, Junichi meets Makihara, the girl who stood him up. To his surprise, Makihara never stood him up because a classmate of hers told her that he was waiting for her at the cinema. On the day of the festival, Risa tells Junichi she wants to end their relationship as she reveals she was the one who lied to Makihara and was also responsible for his heartbreak. Not only that, she reveals that she also sabotaged his relationships with the other girls who were interested in him as well. Feeling guilty, Risa tells Junichi he deserves someone better than her, but he forgives and claims that he feels better now that he knows the truth and still loves her. Risa is glad that Junichi has forgiven her and later apologizes to the girls that she lied to before spending the festival with Junichi.
She can be seen peaking on Junichi in all main heroines OVA.
She only appears in Miya Tachibanca arc. Having chat with Keiko Tanaka.
A one-shot story about her date with Junichi on the beach is shown in "Amagami Precious Diary" as a bonus chapter.
In her route, she is a secret character.
If Junichi rejects her, she does not forgive him and exposes his porn magazines to the school as revenge. She does this, believing that if she can't have him, nobody else will. Due to this, his friendship with Umehara and Kaoru is ruined and even Miya becomes distant to him.