Hikari Mitani. A 27-year-old woman living in the apartment next to the protagonist. First person: I (polite/feminine). She is the primary personality of Hikari Mitani. The two became close after lending each other an umbrella on a rainy day. Though she has a baby face, she has a mature, meddlesome older-sister personality. She is a skilled cook and often prepares meals for the protagonist, worrying about his dietary habits. She has had multiple personalities since birth and originally thought the others were imaginary friends. She has a history of isolation due to this condition. As a rule, the personality switches every day, but changes can occur during emergencies. Memories are shared between personalities, so there are no gaps in conversation. She can communicate with the other personalities inside her head. She views the protagonist as a good person and a friend. She calls Hikaris "Hikaris" and Hikarin "Hikarin".

One of Hikari Mitani's personalities. First person: I (soft/polite). The second personality to emerge after Hikari-san. She is quiet and soft-spoken. She was born from Hikari's desire to share her hobbies; when talking about her interests, she speaks rapidly and incessantly. The name Hikaris comes from a "Warrior of Light" character Hikari fantasized about during her student days. Her interests are broad, covering not just anime, manga, and games, but also travel, pickles, and even food smoking. She claims she is fulfilling Hikari-san's desires and has no intention of disappearing, but thanks to the protagonist, she has begun to think that having someone to talk to might make disappearing not so bad. She calls Hikari-san "Hikari-san" and Hikarin "Hikarin".

One of Hikari Mitani's personalities. First person: I (casual/feminine). She is bright, friendly, and gets along with everyone. She was created from Hikari's repressed desires during her student years. Due to her origin, her thoughts and behavior resemble a 17 or 18-year-old. Driven by a desire to do "student-like" things, she loves karaoke and cafe hopping. She is poor at studying and detailed work, often trying to leave those tasks to Hikari-san. She is very physically affectionate and will hug the protagonist upon meeting. Her hobby is badminton. She loves seeing people having fun. She loves the other personalities and sometimes talks about them from an outsider's perspective. Since memories are shared, she often blushes when teased about those comments. She views the protagonist as a good person and a friend. She calls Hikari-san "Hikari-san" and Hikaris "Hikaris".