: The human tennis player caught between Hihi's harsh training and her own career.
: The episode parodies the "#metoo" era and the shifting standards of discipline in Japanese education and sports, often showing how legitimate concerns can sometimes spiral into absurd or bogus claims.
The story centers on , a gorilla-like yōkai and old friend of Medama-oyaji, who has developed an intense obsession with human tennis. Under the human alias "Coach Hihimura," he begins training a young athlete named Yumi Okakura. However, his old-school, aggressive coaching methods quickly clash with modern sensibilities:
: After Hihi is exposed as a yōkai by Nezumi-otoko, Yumi eventually finds a much more literal form of "unbreakable defense" by hiring the wall-yōkai Nurikabe as her new coach. Key Characters
: The guest yōkai whose "passionate" tennis coaching becomes the center of a media firestorm.
: The opportunistic "Rat-man" who, as usual, complicates the situation by tipping off the media for his own gain.