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