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