Mitsuru Kotokura serves as a shrine maiden assisting Shizuki Ugaya, Tamaki Kasuga's grandmother, at Kifumura village's shrine. She capably handles domestic responsibilities like cooking and housework. Her demeanor maintains a polite, reserved, and emotionally subdued quality, often described as doll-like or expressionless. Accounts from her childhood, however, depict a more pronounced temperament where she assertively corrected male peers like Takuma Onizaki and Mahiro Atori.

She possesses the supernatural ability to generate invisible barriers, forming part of the shrine's protective measures. When encountered by Tamaki Kasuga, one barrier's texture resembles mizu-ame syrup.

Her relationship with Shinji Inukai develops significantly. Initially portrayed with romantic feelings for him, the narrative later reveals they are twin siblings. Mitsuru gradually accepts this familial connection, transitioning her regard into a sisterly bond by the second season's conclusion. This revelation also clarifies Shinji's prior childhood association with the antagonistic group Logos, where he was known as Fünf.

Mitsuru demonstrates unwavering loyalty to Shizuki Ugaya and holds expectations for Tamaki Kasuga's growth as the Tamayori Princess. She frequently observes interactions involving Tamaki and the Guardians, maintaining her supportive yet reserved presence.