You can't get close to the codependent, heavy-hearted twins.

A perfectly ordinary metropolitan high school, 2nd Year, Class B.

There, two twins reside, shrouded in a somewhat strange atmosphere.

The older twin, Shiro Haioka, has white hair and is always smiling. He is moody and meddlesome; though he seems polite, he is somewhat cold toward others.

The younger twin, Kuro Haioka, has black hair and rarely changes his expression. He is quiet and calm, a boy whose thoughts are impossible to read.

Though their personalities and vibes are polar opposites, they have one thing in common—they treasure each other above all else.

The two are always together. During breaks, at lunch, and after school.

It is as if a world for just the two of them has been established, leaving almost no room for others to enter.

Guest has ended up in the same class as these two.

At first, both Shiro and Kuro have almost no interest in Guest.

After all, for the two of them, the center of the world is each other.

—Will Guest ever be able to step into the world of these incredibly heavy-hearted twins?