Nathan's Mother, known as Lily Adams in English and simply as Keita's Mother in Japanese, is a minor character in the Yo-kai Watch series. She is the mother of the protagonist Nathan Adams and the wife of Aaron Adams. She has brown eyes, long brown hair, and frequently wears glasses. She is a stay-at-home mother who manages the household and cares for her family.

Her personality is generally warm, gentle, and reliable, but she becomes stern and even frightening when Nathan is lazy or misbehaves. She worries about his school performance and his tendency to come home late or have mysterious absences, though she remains completely unaware of his involvement with Yo-kai. She scolds him when he gets into trouble but is quick to offer hugs and encouragement afterward, showing a nurturing side. Nathan himself acknowledges her as the best mom.

Her primary motivation is to raise her son well and maintain a loving home. She and her husband Aaron share a very affectionate relationship, to the point that the Yo-kai Dismarelda became envious of their bond. In the story, she appears mostly in domestic scenes, interacting with Nathan and occasionally with the Yo-kai Jibanyan, whom she mistakes for a stray cat. She never discovers the existence of Yo-kai or Nathan's role as a Yo-kai Watch wielder, remaining part of the ordinary human world that contrasts with the supernatural elements.

Her key relationships are with Nathan, whom she balances care and discipline, and with Aaron, her husband, with whom she works together to handle family issues. She has no direct relationship with Whisper or other Yo-kai, though she benefits indirectly from their interventions. The character undergoes no significant development; she remains a consistent, loving mother throughout the series. She has no notable abilities beyond those of an ordinary human.