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 Serra's Ending
Achieve the Harem Ending
Together in the Ferris Wheel
"Save" Serra
Go back to Heaven
Receive your punishment
Give in to puppy eyes
Get Mitsuki's Ending
Mitsuki's flawless plan
A friend always helps
Find the helpless Mitsuki
Get Serra into your bed
Finally your aim paid off
It's made with love
Unexpectedly effectful
Just doing a Cupid's job