Here is the full list of all 69 Angel Wings achievements.
Unlock Jei's Good Ending
Complete any route
Unlock all Jei outfits
Begin a Route Selection campaign
Select the Hierophant card
Select the Hermit card
Tell Jei the truth
Unlock Jei's Medium Ending
Complete the game once
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
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
Jump into the hotel pool
Unlock Hyedong's Medium Ending
Unlock Hyedong's Good Ending
Unlock all Hyedong outfits
Go skating
Control your emotions
Fight!
Unlock Nuri's Medium Ending
Unlock Nuri's Good Ending
Eat chicken together
Win a basketball game
Follow Jihyun
Unlock Seola's Medium Ending
Complete an activity with Yujeong
Take a coffee break
Eat ramen with Yujeong
Choose to help Yujeong
Receive the sheet music
Unlock all Yujeong outfits
Enter the drum studio
Unlock all outfits
Complete all routes
Reject the current timeline
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