Birthday: January 4
Zodiac sign: Capricorn

A shy, quiet girl from class 1-4, one door down from Makoto and Sekai's class.

Due to her striking appearance, she's always been somewhat frightened of boys. She is disliked by the girls in her class, and distanced from the boys, who restrain each other from approaching her. Having taken an interest in Makoto as he watches her from afar, she decides to accept when he confesses with the help of Sekai's mediation.

In the last episode of the anime series:
She is the one who kills Sekai after learning about the Sekai's involvement in Makoto's murder. After exacting her "vengeance", she cuts open her stomach to see if she was lying about being pregnant with Makoto's child, where it is revealed that Sekai was not actually pregnant.

She is finally seen on a boat, holding Makoto's head in her arms, finally "united" with the man she loves.
Manga spoiler:
At the end of the manga, she has been stabbed by Sekai, but the situation was not shown. It was only told by Kokoro through the phone that her sister is bleeding a lot and Sekai gave herself away by smirking in front of Makoto.