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