Plot Summary:The story revolves around Rito Yuki, a high-school student who cannot confess to the girl of his dreams, Haruna Sairenji. One day when coming home and sulking in the bathtub, a mysterious, nude girl appears out of nowhere. Her name is Lala and she comes from the planet Deviluke, where she is the heir to the throne. Her father wants her to return to her home planet so she can marry one of the husband candidates. But she decides that she wants to marry Rito in order to stay on Earth. Commander Zastin has been ordered to bring Lala back and has already battled Rito. He reports to the emperor that Rito would be suited to marry Lala, after hearing Rito, who was actually defending himself instead of Lala, say that marriage is impossible unless it is with the person you love. Lala truly falls in love with Rito and decides that she wants to marry Rito after hearing what he said. Her father decides that, if Rito is able to protect Lala from her fiancés, then he can marry her. However, if Rito cannot protect Lala from her other fiancés and meet the king's expectations, Lala's father will kill Rito and destroy the Earth.
结城梨斗(渡边明乃 配音)正派开朗,细心友善。一直以来,梨斗都暗恋着青梅竹马西连寺春菜(矢作纱友里 配音),可是,对于恋爱一窍不通的梨斗只是将这份强烈的感情深深的埋藏在心底。终于,梨斗再也无法压抑心中对于春菜的爱意了,再三地鼓起勇气,他决定向春菜表白。 一次偶然中,一位名叫菈菈(户松遥 配音)的女孩从天而降出现在了梨斗的面前,在阴差阳错之间,菈菈竟然成为了梨斗的告白对象,就这样,梨斗和自称是外星公主的菈菈开始了同居生活。也就是从这时开始,杀手暗影(福圆美里 配音)、菈菈的妹妹娜娜(伊藤加奈惠 配音)和梦梦(丰崎爱生 配音)等人接二连三的来到了梨斗的身边。