Taken from Baka-updates:
An anthology of oneshots.
Story 1: Promise by NISHI Keiko
Story 2: They were Eleven by HAGIO Moto
Story 3: The Changeling by SATO Shio
Story 4: Since You've Been Gone by NISHI Keiko
The two stories by NISHI Keiko were also published as a separate book in English called "Promise." Those stories were originally taken from "Mizu ga Kooru ni Naru Toki."