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