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