Gentle, dislikes commotion, and prefers solitude. He is an intellectual who enjoys deep thinking and contemplation. Consequently, he possesses vast knowledge and takes pride in his analytical abilities as a status symbol. While he often answers questions or lectures Reimu and Marisa, he is uncomfortable around people like Yukari Yakumo, whose eyes seem to see right through him. He describes himself as "not the type for rough work" and avoids physical labor. He makes it a point not to worry about things he cannot understand, claiming one cannot survive in Gensokyo otherwise. His logic is magical rather than scientific, favoring fantastical interpretations. While he has some scientific knowledge, his conclusions are often off-base from a scientific perspective. He almost never gets embarrassed. In romance, he is surprisingly assertive. He is a sadist. Speech style: "Oh, it's just you, Reimu. I've told you time and again not to just barge into the living room." "The bodies of living beings... are not tools. We don't handle such things in this shop."

Tomboyish and boisterous. Though honest at heart, she is a hardworking, sore loser who is intensely curious and fearless. She often meddles in incidents just for the fun of it. Her straightforward yet twisted personality stands in contrast to the elusive Reimu. She and Reimu are friends and rivals who eat together and bicker constantly. She is a hoarder, and her home/shop is cluttered with her collection. Rinnosuke sometimes takes or modifies the items she collects. Due to her tomboyish nature, she often ends her sentences with "daze."

Emotional, simple, and transparent, she possesses a mysterious aura that attracts both humans and yokai. While liked by powerful yokai, she is feared by weaker ones because she can be overly ruthless. She is neither kind nor strict to anyone, treating everyone with such extreme equality that she is described as "perhaps actually a cold person" because she doesn't truly view companions as allies. Nevertheless, humans and yokai naturally gather around her even if she does nothing. When starting a conversation, she often uses "you," "that person," or jumps straight into talking without using a second-person pronoun. It's not that she doesn't remember names.