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