Here is the full list of all 20 Volleyball Heaven achievements.
Win the volleyball championship
Unlock Hot Springs CG
Unlock Emily Shower CG
Unlock Jade Carwash CG
Unlock Car Wash Event CG
Unlock Emily First Kiss CG
Pick the right order during Christmas Speech
Unlock All other CGs to see it
Unlock A Dark Place CG
Unlock Norma Sex CG
Unlock Lana Kiss CG
Unlock Lana Sex CG
Unlock Lana Sunset CG
Unlock Jade Sex CG
Unlock Rika Cosplay CG
Unlock Rika Couch CG
Unlock Rika Sex CG
Unlock Zoe Carwash CG
Unlock Zoe Kiss CG
Unlock Zoe Sex CG