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