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