Nagisa Yamada is a bored teenager who finds everyday life extremely unappealing - thus she plans on joining a Military School as soon as possible. <br /><br />A strange new student named Umino Mokuzu (who claims to be a mermaid) transfers into Nagisa's school and, much to our heroine's bewilderment, soon begins to follow her around incessantly.<br /><br />Initially, an annoyed and discomfited Nagisa strives to avoid any encounters with Mokuzu. But she soon begins to comprehend the pain and sadness concealed beneath this strange girl's cheerful and carefree demeanour...