Classmate, Kamimura Yuuka wa Kou Itta

Shirasaki is bored by the sameness of his everyday school life until he gets drawn into the orbit of his unusual classmate, Kamimura Yuuka. She talks to her uninterested classmates about changing the world, but Shirasaki soon learns that their world is not what he thought it was. That revelation sends his ordinary routine in a direction stranger than he could have expected.