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