Here is the full list of all 60 1bitHeart achievements.
See the Bad End
See the Normal End
Get GAME OVER
Play the Extra Story
Befriend Mikado
Befriend Misane
Befriend Tobari
Complete all friendships
Befriend Kirai
Befriend Nomiya
Befriend Kotora
See the Happy End
Befriend Mary
Befriend Meru
Befriend Saaya
Befriend Izuchi
Befriend Hitohito
Befriend Sagara
Befriend Meu
Befriend Potete
Befriend Aira
Begin Chapter 4
Befriend Kirara
Befriend Ryuuri
Befriend Yuuto
Befriend Hiyu
Befriend Jin
Befriend Asuto
Befriend Enri
Befriend Azusa
Befriend Akitaka
Begin Chapter 3
Befriend Momori
Make 25 friends
Befriend Misato
Befriend Sora
Befriend Moroku
Befriend Akashi
Befriend Chino
Befriend Rocca
Befriend Haruya
Begin Chapter 2
Befriend Sekiyu
Befriend Akuta
Befriend Yukinaga
Befriend Sakuma
Befriend Nio
Befriend Miumi
Befriend Kiri
Give someone chocolate for the first time
Befriend Kuroku&Shiroro
Befriend Shiren
Befriend Kaori
Befriend Shitara
Befriend Natsukage
Befriend Hakuhi
Befriend Takamiya
Befriend Yasune
Find the Cheat Code (bottom-right of Bit World...)
Begin Chapter 1