Here is the full list of all 16 Sakura Cupid achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Get Mitsuki's Ending
Get Serra's Ending
Finally your aim paid off
Go back to Heaven
Receive your punishment
Achieve the Harem Ending
Mitsuki's flawless plan
A friend always helps
Find the helpless Mitsuki
Get Serra into your bed
Together in the Ferris Wheel
"Save" Serra
It's made with love
Give in to puppy eyes
Unexpectedly effectful
Just doing a Cupid's job