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