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