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