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.
Give Damien his Humanity.
Get Proposed to by Andrew.
Be Eaten Alive by Diana's Pit Beast.
Be Baptized by Angels.
Start your Adventure with Diana.
Rename the Main Character.
Preview the start of Seduce Me 2: The Demon War!
Witness Simon's Transformation with Diana and someone special...
Obtain True Power.
Obtain True Freedom.
Impress the House Party Guests.
Get Shot in the head by Malix.
Dodge Malix in time.
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 Proposed to by James.
Find Harold Anderson's Magic Books.
Prove Your Love to Suzu.
Go To Paris with Naomi.
Unlock the Second Set of Bloopers!
Fight Malix Yourself.
Unlock the First Set of Bloopers!
Prologue Completed!