Tohko Yotsuya is the wife of Mamoru Yotsuya and mother to Miko and Kyousuke Yotsuya. Her chest-length jet black hair is typically tied into a low side ponytail with a light blue scrunchie, resting on her right shoulder. The style includes bangs swept left and chest-length strands framing her face, complemented by golden eyes. She met Mamoru, settled down with him, and had their two children, sharing a household with Miko and Kyousuke. Her surname "Yotsuya" combines the kanji for "four" (四) and "valley" (谷), while her given name "Touko" means "transparent, permeate, filter, penetrate" (透) and "child" (子).