For many years now, Masaki and Rion have shared a close bond as lifelong friends. Although their personalities are quite different, they enjoy spending time with each other and even live together as adults. However, beneath their casual camaraderie lies a deeper emotional connection that has yet to be acknowledged by either of them. Recent events such as the birth of Rion's ex-girlfriend's child and memories of their shared past with an old kouhai from school bring back feelings that were once buried deep within their minds. Will these emotions finally surface and allow their friendship to develop into something more?