Alien Guts, also known as Gattsu Seijin, is a recurring Ultra franchise alien species. This character manifests anthropomorphically as Miko Innami, a female human with distinctive orange eyes and long hair featuring white, blue, and yellow coloration. Miko exhibits a cocky personality coupled with a powerful work ethic, readily accepting diverse missions ranging from combat operations and search missions for stray kaiju girls to bodyguard duties. This drive stems from her determination to uphold the invincible legacy of Alien Guts and prevent tarnishing its reputation.

Inheriting core abilities from Alien Guts, Miko possesses teleportation and duplication powers activated upon assuming her kaiju girl form. An unexplained partial possession by a shadow mist triggered an unconscious duplication during her sleep. This resulting duplicate became fully possessed by the mist, emerging as a distinct entity known as Shadow Guts – a significant event in her background.

Miko's narrative role begins during a bodyguard assignment for Clala, where she first encounters the character Aki after defeating a shadow mist possessing another individual. Her story further develops as she contends with the consequences of her duplicated self and the emergence of the Shadow Guts entity.