Ritou Seiki, known in Japanese as 離島棲姫 (Ritou Seiki), is a prominent antagonist in the Kantai Collection (KanColle) series. She is one of the Abyssal Fleet's elite bosses, often depicted as a menacing and powerful foe who confronts the fleet girls. Ritou Seiki is characterized by her imposing appearance and formidable abilities, symbolizing the threat of remote islands. Her role in the series is to provide significant challenges to players, acting as a major adversary in several event operations.