Koishi Komeiji is a satori youkai and the younger sister of Satori Komeiji. She has trouble sitting still and has a long history of sneaking her way out of the Palace of the Earth Spirits, only to later be found wandering around aimlessly.

Satori youkai have the ability to read other people's thoughts. As a result, it seems they tend to be despised by not only humans but also other youkai and vengeful spirits. Koishi's older sister's attempted solution to this problem was to hide away in the Palace of the Earth Spirits and avoid all contact with outsiders. Koishi, meanwhile, opted to seal away her ability entirely.

Both the Komeiji sisters have a third eye on their chest. This third eye is supposedly the key to their satori youkai ability to read thoughts. Apparently, Koishi closed her third eye, thus sealing off her ability. It seems the connective cord extending from a satori youkai's third eye can be used to attack enemies in a similar fashion to a tentacle.

Koishi once claimed, "Reading people's minds only brings sadness. There's nothing good about it." When she closed her third eye, she accidentally sealed off her mind. In doing so, she gained the seemingly peaceful ability to manipulate both her own and other people's unconscious minds. This freed her from the shackles of her own consciousness, allowing her to act without thinking.

Koishi is still able to act subconsciously, and at some point, she learned how to manipulate others' unconscious minds so as not to be detected when she's on the move. She now lives in a world devoid of conscious thought and detection by others. If you could consciously process a world like that, what would it possibly look and feel like? As of yet, none who can answer that question have appeared.