This is actually a collection of some old side stories of Yuu Watase.
Volume 1:
Story 1 - "Sunde ni Tiara" in "Imadoki" Vol. 5
Story 2 - "Couple" in "Shishunki Miman Okotowari Kanketsu Hen"
Story 3 - "Hatsuki Triangle" in "Suna no Tiara"
Story 4 - "Houkago Gensou" in "Appare Jipangu" Vol. 1
Story 5 - "700 Nichi no Blue" i...