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