Miho Mukai is a twelve-year-old student who shares a close friendship with Haruka Kaminogi, Yuu Gotou, Isami Fujiwara, and Ai Hasebe in their present-day timespace. She is a cheerful, bespectacled girl with a deep and persistent fascination with the paranormal, enthusiastically believing in ghosts, aliens, UFOs, Ouija boards, and other supernatural phenomena. Her obsession often tests the patience of her friends, yet she occasionally proves surprisingly perceptive, as some of her theories about alien abduction turn out to be correct within the story's multiverse framework.

Miho's role in the narrative is primarily as a supportive member of Haruka's circle, but she becomes more personally involved when she encounters Atori, a Dragon Cavalry member from the future who has lost his memories. Mistaking Miho for his sister, Atori grows attached to her, and Miho responds with kindness and concern. When Atori shows signs of reverting to his previously violent and unstable state, Miho's genuine distress—expressed through tears and a threat to stop speaking to him—is enough to pull him back to his calmer demeanor. This moment highlights her emotional sincerity and her ability to reach others through simple, heartfelt connection.

An alternate timespace reveals a darker potential future for Miho, one in which her family's wealth isolates her from her peers, leading to deep loneliness and eventual psychosis after she locks herself in her room for two weeks. In that timeline, it is again Atori who intervenes and helps her regain her grip on reality, though the story indicates that this outcome is not her destined path. In the primary timeline, Miho remains a vibrant, if eccentric, friend who adds levity to the group and unknowingly serves as a bridge between the ordinary world and the extraordinary events unfolding around her. She has no supernatural abilities of her own, but her unwavering curiosity about the unknown makes her receptive to the strange occurrences that define the series.