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