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