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