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