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