Masaru and Nao grew up together like real siblings and developed a very special bond, even though they have no real blood ties.
So much so, that Masaru begins to develop a strong crush on her Sister, and he is about to declare himself.
At the same, he confides his feelings to his best and only friend: Yudzuru. Who listens in awe to the story of his friend, and begins to feel jealous of his happiness…