Emi Daimonji serves as the middle sister among the Daimonji siblings, flanked by Saki and Yu. She works as a nurse at a local hospital, characterized by brown shoulder-length hair, yellow eyes, and a height of 1.61 meters with measurements of 88-59-87. Her standard attire is a pink nurse uniform.

Emi competes in a martial arts tournament centered on claiming the Martial Heart, a jewel granting any wish. In combat, she repurposes medical equipment into weapons: launching syringes as projectiles and wielding durable gauze bandages like whips to entangle opponents' limbs. During the tournament, she allies with her sisters to recruit the protagonist, Aya Iseshima, into their group.

After her defeat, Emi falls under Miko Kazuki's enslavement, mirroring the fate of other losing combatants. This subjugation involves mind control that diminishes her mental faculties.