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