Here is the full list of all 13 Chuusotsu! 1st Graduation: Time After Time achievements.
Meet Arara
Meet Arue
Complete all achievements in Chuusotsu - 1st Graduation
Finish Proposition 1
Finish Proposition 2
Finish Proposition 3
Complete the Game
Meet Koiro
Meet Kokoro
Meet Holo
Meet Froit & Yung
Spend a Day at the Beach
View the extra scenario