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.
Be Baptized by Angels.
Preview the start of Seduce Me 2: The Demon War!
Obtain True Power.
Obtain True Freedom.
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.
Get Proposed to by Andrew.
Start your Adventure with Diana.
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.
Find Harold Anderson's Magic Books.
Get Proposed to by James.
Unlock the Second Set of Bloopers!
Unlock the First Set of Bloopers!
Dodge Malix in time.
Prologue Completed!
Rename the Main Character.