In Luvdisc is a Many Splendored Thing!, it was revealed that Misty and Daisy had both obtained Luvdisc of opposite genders, in the hope of using them in one of the Cerulean CityGym's water ballets. Caserin was in love with Luverin, but Luverin completely ignored Caserin's advances.
Meanwhile, Dr. Namba had concocted an evil scheme to rid the world of love and needed the two Luvdisc as his key components. To his aid, Butch and Cassidy were asked to steal the Luvdisc (in the original Japanese version, Dr. Namba only wanted them for his "R-project", not mentioning anything about ridding the world of love at all). His plans were ruined, however, when Caserin and Luverin were able to cooperate and save each other. Seeing Caserin's heroic acts, Luverin fell in love with him. Their mutual attraction finally allowed Daisy to complete her new show.
Personality and characteristics
Caserin was lovesick and easily saddened when Luverin would turn him down. However, with Misty's encouragement, Caserin was able to save both himself and Luverin, causing the latter to fall in love with him.
Caserin is the only Pokémon belonging to a main character to have never appeared in the main series in any capacity.
Caserin is the first Pokémon Misty owns with a confirmed gender.
Caserin and Luverin's names are a play on both the name Catherine and the two syllables of Lovecus, the Japanese name of Luvdisc. Caserin also contains a part of Misty's Japanese name, カス Kasu.
