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.
Turn down sex, but keep your true love.
Preview the start of Seduce Me 2: The Demon War!
Impress the House Party Guests.
Witness Simon's Transformation with Diana and someone special...
Get Shot in the head by Malix.
Be Eaten Alive by Diana's Pit Beast.
Be Baptized by Angels.
Start your Adventure with Diana.
Obtain True Power.
Obtain True Freedom.
Get Proposed to by Andrew.
Dodge Malix in time.
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.
Rename the Main Character.
Get Proposed to by James.
Kiss Erik under the Moonlight.
Find Harold Anderson's Magic Books.
Unlock the First Set of Bloopers!
Unlock the Second Set of Bloopers!
Prologue Completed!