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