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