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