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