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