Here is the full list of all 15 My Klutzy Cupid achievements.
Started the game
Started Eil's route
Started Izusu's route
Started Rinka's route
Reached Uta's ending.
Started Kotohina's route
Started Kururu's route
Reached Eil's ending.
Reached Isuzu's ending.
Reached Rinka's ending.
Started Uta's route
Reached Kotohina's ending.
Reached Kururu's ending.
Reached Masora's ending.
Obtained all achievements.