Here is the full list of all 69 Angel Wings achievements.
Unlock Seola's Good Ending
Follow Jihyun
Unlock Nuri's Good Ending
Unlock Hyedong's Good Ending
Unlock Yujeong's Good Ending
Receive the sheet music
Eat ramen with Yujeong
Unlock all Jei outfits
Unlock Jei's Good Ending
Tell Jei the truth
Begin a Route Selection campaign
Select the Hierophant card
Unlock Yujeong's Medium Ending
Choose to help Yujeong
Unlock all Hyedong outfits
Take a coffee break
Go to the mall with Chaeng
Complete an activity with Yujeong
Select the Hermit card
Unlock Nuri's Medium Ending
Control your emotions
Go skating
Unlock all Seola outfits
Unlock Seola's Medium Ending
Defeat Kaori
Play video games together
Win a basketball game
Eat chicken together
Complete any route
Complete the game once
Unlock Hyedong's Medium Ending
Jump into the hotel pool
Help out with cooking
Attend the work party
Party time!
Go to the forest together
Attend the beach
Buy some food
Complete the lake run
Eat salad together
Choose stealth mode
Visit the phone shop
Stick around for extra practice
Complete the work assignment
Complete an activity with Seola
Enter the bar
Meet Nuri
Select the World card
Pick up the phone
Check the computer
Unlock Kei's ending
Unlock all Kei outfits
Leave class early
Watch drama together
Give Chaeng the phone
Unlock Chaeng's Medium Ending
Unlock Chaeng's Good Ending
Unlock all Chaeng outfits
Unlock Jei's Medium Ending
Fight!
Unlock all Yujeong outfits
Enter the drum studio
Unlock all outfits
Complete all routes
Reject the current timeline
Unlock all Nuri outfits
Complete the band
Unlock Yuri's Ending
Unlock the true ending