Kokoro is a pretty classmate of Kippei. Because she lost her mother at a young age, she has a quiet personality. Her father quickly remarried and left Kokoro to fend for herself in a luxurious apartment, believing that because she was quiet, she would prefer to live alone. This is not the case, however, and she feels extremely lonely living by herself with no one else to rely on. Kokoro initially despises Kippei for his promiscuous ways. However, after seeing how gentle he is and how much he cares for Yuzuyu, Kokoro begins to fall in love with him. Kokoro sympathizes with Yuzuyu and understands Kippei's responsibility for Yuzuyu. As such, she lets him get away with a lot of idiotic behavior. At the end of volume six, for a brief time, Kokoro believes she's pregnant, only to find out that it was a false alarm. However, she admits to Kippei that she had hoped she was pregnant, despite the problems that would arise, because it would mean that she would be able to spend more time with him. Soon after, Kokoro moves in with Kippei's family. At the end of the manga, Kokoro and Kippei are living with his parents and it is implied that they are married.