Yesterday wo Utatte EX – Genten wo Tazurete Toume Kei Shoki Tanpenshuu

A special volume containing background/design information on the main series, some extra side stories, as well as some early works by Kei Toume.

The Sea Where the Siren Lives:

"In the city by the sea, we understood that we could never understand each other."

Related:
Yesterday wo Utatte:
http://bato.to/comic/_/yesterday-wo-utatte-r748