Here is the full list of all 15 Kinkoi: Golden Loveriche achievements.
Finish Reina's Route
Finish Akane's Route
Start Akane's Route
Finish Sylvia's Route
Start Reina's Route
Start Elle's Route
Start Sylvia's Route
Finish Common Route
Start a new game
Finish Elle's Route
Start Ria's Route
Finish Ria's Route
Reach the True End
Unlock the Hidden Special End
Unlock all Achievements