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