Mayo Chiki! follows Kinjirou Sakamachi, a boy whose body has been hardened for years by training with the wrestling-loving women in his family. He can shrug off hard punches, aggressive kicks, and even deadly vehicle bumps, but that toughness comes with a serious weakness: gynophobia. A single touch from a girl can leave him with uncontrollable nosebleeds, heavy sweating, or even sudden fainting.
His carefully managed life is thrown into chaos after a fateful encounter in a school restroom. While trying to escape from a girl, Kinjirou discovers that Subaru Konoe, the school’s most popular student and the butler of Kanade Suzutsuki, the headmaster’s daughter, is actually female. Subaru reacts with a violent beating that leaves Kinjirou unconscious, and the situation only becomes stranger when he wakes up to find Kanade waiting for him. She makes him an unusual offer: if he keeps Subaru’s secret, she will help him cure his phobia.
From that moment on, Kinjirou is trapped between Subaru’s secret, Kanade’s bargain, and the constant challenge of surviving daily life with a condition that makes every close encounter with a girl a potential disaster.