Gousuke Guden serves as a keeper at Gama Gama Aquarium, resuming duties after medical leave for lumbago just as Fūka Miyazawa joins the facility. His familiarity with idol culture allows him to identify Fūka's past career immediately upon his return, making him among the earliest to learn her secret. When Gama Gama permanently closes, Gama Gama's director facilitates his transfer to Tingarla Aquarium. Personally, he savors Shochu Ice Cream and holds a special admiration for the aquarium's frogfish.