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