- "...It's sneaky to come over here because of that. It takes courage to look at one's faults.But if you think you've done something wrong... then you should live with that guilt and pain. To live with that self-loathing, writhing with agony inside your heart, is a worse punishment than coming over here."
- ―Koharu to her son
Although she has been dead for more than ten years by the beginning of the series, she appears throughout the manga in memories, photos, and flashbacks.
In the manga, after he was stabbed in the arm by Komori and was suffering a severe blood loss, Akito nearly died. He had an out-of-body experience and began walking around the hospital. He found a door, but before he could enter the room behind it, Koharu appeared from inside and said he was too young to be entering that room, meaning that he was too young to die. Akito said he didn't want to go to that room but he would because he made two girls (Sana and Fuka) cry. Koharu said that it was a worse punishment to live with that pain instead of dying and encouraged him to live. When Akito realized that she was his mother, Koharu apologized for not being able to raise him. Then she repeated Sana's words from Volume One, telling Akito that she loves him and that she gave birth to him because she wanted him to be born no matter what. After Akito realized these words were spoken to him originally by Sana, his pulse returned and Koharu stood next to him in the emergency room as the doctors rediscovered his pulse.