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