Here is the full list of all 69 Angel Wings achievements.
Complete an activity with Seola
Meet Nuri
Select the World card
Unlock Hyedong's Medium Ending
Unlock all Hyedong outfits
Complete any route
Complete the game once
Jump into the hotel pool
Help out with cooking
Attend the work party
Go to the forest together
Attend the beach
Take a coffee break
Eat salad together
Visit the phone shop
Complete the work assignment
Complete an activity with Yujeong
Enter the bar
Select the Hierophant card
Pick up the phone
Select the Hermit card
Check the computer
Unlock Kei's ending
Unlock all Kei outfits
Leave class early
Go to the mall with Chaeng
Watch drama together
Give Chaeng the phone
Unlock Chaeng's Medium Ending
Unlock Chaeng's Good Ending
Unlock all Chaeng outfits
Unlock Hyedong's Good Ending
Choose stealth mode
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
Complete the lake run
Eat chicken together
Win a basketball game
Follow Jihyun
Stick around for extra practice
Unlock Seola's Medium Ending
Eat ramen with Yujeong
Choose to help 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
Play video games together
Unlock Yujeong's Medium Ending
Unlock Yujeong's Good Ending
Complete the band
Unlock Yuri's Ending
Defeat Kaori
Unlock the true ending