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