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