Here is the full list of all 25 Seduce Me the Otome achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Share some Cake with Matthew.
Go To Paris with Naomi.
Witness Simon's Transformation with Diana and someone special...
Prove Your Love to Suzu.
Be Baptized by Angels.
Start your Adventure with Diana.
Obtain True Power.
Preview the start of Seduce Me 2: The Demon War!
Get Proposed to by James.
Obtain True Freedom.
Turn down sex, but keep your true love.
Get Shot in the head by Malix.
Find Harold Anderson's Magic Books.
Prologue Completed!
Rename the Main Character.
Kiss Erik under the Moonlight.
Accept Sam for the Man he is.
Give Damien his Humanity.
Get Proposed to by Andrew.
Be Eaten Alive by Diana's Pit Beast.
Unlock the Second Set of Bloopers!
Fight Malix Yourself.
Unlock the First Set of Bloopers!
Dodge Malix in time.
Impress the House Party Guests.