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