Isohgin (spelled as イソーギン or Isōgin) is a member of the antagonistic organization Eternal. He operates exclusively as one half of a duo alongside Yadokhan, collectively known as Eternal's "best hunters." Depicted as tall and largely silent, Isohgin primarily echoes or repeats phrases spoken by his partner Yadokhan during their missions.

Their primary battle tactic involves combining into a single composite entity. In this merged form, Isohgin constitutes the upper section resembling a sea anemone, while Yadokhan forms the lower hermit crab segment. This amalgamation is their standard approach when confronting the Pretty Cure protagonists under Eternal's directive to obstruct them and obtain the Rose Pact to access the Cure Rose Garden. The character remains defined by his role within this duo and their function within Eternal's hierarchy.