Tsugiko Zenigata is Inspector Zenigata's mother, appearing exclusively in the Summer Special. She embodies a traditional, doting maternal role, expressing deep affection and concern for her adult son's well-being. Her focus centers on his eating habits and perceived loneliness, manifesting through actions like delivering homemade meals and bento boxes to provide nourishment and care. Her overly affectionate behavior often embarrasses Inspector Zenigata, causing him visible discomfort. She persistently seeks involvement in his life, including his work, though her understanding of his detective duties remains superficial. Her presence generates comic relief through the contrast between her smothering maternal instincts and her son's serious, easily flustered demeanor. Her role is confined to this Summer Special episode, with no appearances in other Milky Holmes media or development beyond her identity as Zenigata's mother.