Tsukuyomi Komoe

Komoe Tsukuyomi (月詠 小萌) is actually an adult and one of Touma's teachers, despite her childish and very short (135cm) stature; this is proven by the fact that her apartment is littered with beer cans, cigarettes and neuropsychology books. She insists her students address her by her first name (Komoe-sensei), and has a very young sounding voice. She contradicts her age by acting in a childish manner towards her students- having a child-like crush on Touma, and ending her sentences with desu- something a child usually does; this irony is why she is often regarded as one of the seven great mysteries of Academy City.

She has a major interest in the studying of magic and performs magic once, with Index's 'Johann's Pen Mode' guiding her, showing she is one of the few non-psychics in Academy City. The second time Komoe came into contact with magic is when she attempted to use magic to help Himegami after she had been attacked by Oriana, though Stiyl intervened, stating her technique was "too crude" and took over healing Himegami using scraps of information that Komoe managed to remember from her first time as a guide.

'Komoe-sensei', who is passionate about teaching, has a weakness. That weakness being the fact that she’ll feel extremely dejected whenever she feels she has lost an opportunity to teach others. This is shown in Volume 9 when she wanted to teach Index how to use chopsticks. She is also very knowledgeable when it comes to human physiology and AIM Dispersion Fields.

In volume 9, it is said by Yomikawa Aiho that Komoe, being a teacher even older than herself, looks scarily fitting in cheerleading clothes, and in the author notes at the end of volume 5, it states that Komoe is currently the oldest female character in the novels.

According to Stiyl, Komoe's personality is much akin to that of Index- "A petite figure, extremely naïve, one who gets angry for other's sake, one who cries for other's sake, one who has magical knowledge, but is unable to use magic. That tearful look when she was dyed in other people’s blood was exactly the same".

Trivia
Her name is an aptronym as the character "小" means "small" and the character "萌" means "moe".