- Shintaro Kisaragi: Shintaro is Momo's brother. She actually worries about Shintaro's well-being, though she does not show it. They act very similar to each other, but she would always deny that. Momo usually nicknames him "stupid big brother". She stated that because of Shintaro's apathetic personality, the two of them rarely talk to each other. When she was small, Shintaro quietly cheered her up when she started to cry. She told Kido and Marry that she wants for them (Mekakushi Dan) to be by his side because deep inside, he had a deep regret that he wouldn't share to anyone. It is because of the attention that was paid to Shintaro by their parents when the two were younger that Momo sought attention for herself, which she eventually received when her ability manifested.
- Kenjirou Tateyama: Kenjirou is Momo's homeroom teacher. He worries about her job, as well as her time at school.
- Hibiya Amamiya: Momo and Hibiya tend to constantly argue with each other. He calls her "oba-san" which means something like old lady in his case. Seeing as Hibiya is constantly haunted by the death of his friend Hiyori, Momo wants to do everything to help him to cheer up again. Eventually it is her support that helps him accept his eye ability.
- Marry Kozakura: After a few problems upon meeting her, Marry grew to be one of Momo's best friends.
- Tsubomi Kido: When she was crying in an alleyway, Kido came across her and led her to the secret hideout. She became a member of the Mekakushi Dan after that. Kido also explained Marry's, Kano's as well as her own eye powers to her. She also calls Kido "leader". She refers to Momo as "Kisaragi".
- Shuuya Kano: Kano was the reason that Momo got to join Mekakushi Dan in the first place, since Kido thought they would be able to get a new member because he joked about it. In the manga, he tried approching Momo, but Momo herself, along with Shintaro, stopped him since they thought he was trying to hit on her. That same time, she actually got mad when Kano said that Hiyori may no longer be alive, which she claimed were lies.
- Ene: Ene and Momo are friends, as Ene has not taken up residence in her computer. However, Momo got mad at her when she asked if there was "yuri" (girl love) between her and Marry. In Mekakucity Actors, Momo defends Ene when Shintaro talks about how obnoxious Ene is. Momo often calls Ene "Ene-chan", while Ene calls her "Imouto-san (little sister)" due to Momo being related to Shintaro, much to being younger than him.
- Hiyori Asahina: Hiyori is a big fan of Momo. Her intention of coming to the city over the summer was based solely on getting an autograph from the young idol, with an inside link providing her access to be able to meet her. In the manga, Hiyori is able to meet Momo and receives her autograph after defending her from a hoard of fans. When Momo gets a disturbing phone call from Hiyori, calling for help and yelling "Stop it!" repeatedly, and later going missing, she intends on finding her, blaming herself as it was she who directed Hiyori to the park where she was last seen.