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