Merman in My Tub - Season 1 Episode 9 My Naked Circumstances
Overview: Wakasa is shocked when Tatsumi leans over the tub and announces it stinks. Tatsumi cleans the tub responsible for the odor and transfers Wakasa to a children's pool. Saying, "Brother, tell me if you're using the pool," Kasumi mistakes Wakasa for Tatsumi and hugs him.