Full list of all 44 恋爱关系/Romance achievements.
The base game contains 19 achievements, and there are 2 DLC packs containing 25 achievements.
Complete Chapter 1
Complete Chapter 2
Complete Chapter 3
Unlock special episode 1
Unlock special episode 2
Unlock special episode 3
Unlock special episode 4
Choose boyfriend shirt for the first time
Choose a bunny girl for the first time
Unlock all CGs
Open FINAL for the first time
Complete Chapter 8
Complete Chapter 9
Complete Chapter 10
Complete Chapter 11
Complete Chapter 12
Complete Ending 1
Complete Ending 2
Choose Nana-Hiroshu for the First Time
Choose Shinta-Chika for the First Time
Complete Chapter 13 twice
Get Understanding From Yuki