From Baka-Updates:
Adapted from "Hada no Ue no Renai Jijou " with the following pairings: Aoki x Mizusawa; Tsukishima x Yamaji .
This is a series of six. The order is:
1. Hada na Ue no Renai Jijou
2. Zaiaku wa Hada no Ue ni (same characters & issue but different plot)
3. Zaiaku wa Hada no Ue ni-Hada no Ue ni Furu Hana*
4. Renai Tsuu
5. Renaitsuu-Akka-*
6. Pillow Talk + Holiday*
(*) indicate djs.
4 and 5 are spin-offs featuring Aoki and are contain events from Zaiaku from Aoki's perspective.
6 features both couples.