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