Atsuko Yamaguchi is Takeshi Chimatsuri's classmate and long-time friend, though her feelings for him extend beyond friendship. She strategically supports his conflict against the Toki twins by crafting countermeasures to level the combat conditions. Atsuko specifically aids Takeshi in developing resistance to the twins' seductive tactics, which target his hypersensitivity to female nudity. During these training exercises, where she participates directly, she observes Takeshi expressing deep gratitude for even minor assistance. This intense appreciation inadvertently helps him temporarily suppress his sensitivity during confrontations.