Yasuko Yokoyama (横山 靖子 Yokoyama Yasuko) is Yumeria's mother-in-law who is secretly an anime otaku whose favorite series was the Ninja Cap-tan (忍者キャプたん Ninja Kyapu-tan) and went by the name Etsuko Horimi (堀美 江都子 Horimi Etsuko) as a anime singer. Though she forbid Yumeria's otaku quirks on the impression that it would tarnish the Yokohama name, Yasuko accepts it after seeing it first hand.