 Infused with the DNA of a Finless Porpoise, Retasu's legs can change into a porpoise's tail while she is underwater, greatly improving her swimming ability and giving her an appearance of a mermaid.In the anime adaptation, this change can only occur when Retasu is in the presence of Mew Aqua.Retasu is portrayed as a shy and intelligent character lacking self-confidence and is the subject of frequent bullying from three girls.