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.
Preview the start of Seduce Me 2: The Demon War!
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.
Share some Cake with Matthew.
Accept Sam for the Man he is.
Turn down sex, but keep your true love.
Kiss Erik under the Moonlight.
Get Shot in the head by Malix.
Be Baptized by Angels.
Obtain True Power.
Impress the House Party Guests.
Get Proposed to by James.
Dodge Malix in time.
Obtain True Freedom.
Find Harold Anderson's Magic Books.
Rename the Main Character.
Be Eaten Alive by Diana's Pit Beast.
Unlock the Second Set of Bloopers!
Fight Malix Yourself.
Unlock the First Set of Bloopers!
Prologue Completed!