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