Kimi wa Hitori ja Nai jan, to Boku no Naka no Hitori ga Itta

Kimi wa Hitori ja Nai jan, to Boku no Naka no Hitori ga Itta (キミは一人じゃないじゃん、と僕の中の一人が言った) is a light novel series by Tomoyasu Higa with illustrations by Mitsuru Hattori.