|Japanese name:||水瀬 秋子|
Akiko certainly exhibits more knowledge of the situation than Yuichi as far as the origins of Ayu Tsukimiya and Makoto are concerned, hinting that she is familiar with the supernatural goings-on in the town and how they apply to Yuichi.
Akiko is very important to Nayuki since she does not have a father.
Akiko is known to be very easy-going and is constantly smiling. She will not even resort to stern lectures, such as when Makoto spends money on herself that Akiko gave her to buy food. Akiko can be assertive, though she never has once raised her voice in anger or otherwise. She will often give responses to questions within one second of being asked, the answer almost always marking approval.