"If your memory returns, I can no longer be with you."

Tomohisa and Yuuta live peacefully on a small island in Seto Inland Sea. Yuuta's lost memory of the past and regressed to an infant-like state, but for some reasons, Tomohisa doesn't want him to regain his memory and continues on living while hiding from something. In a closed-off world, Tomohisa, immersed in a distorted happiness, seems to always see the trace of "someone" in Yuuta…?