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