Fifty years ago, Sophia met Anton at one of Duke Herzen's parties, and after going out with him for a while, she and him fell in love and became engaged. She was the youngest daughter of another noble family of Folsense, which had wealth almost equal to the Herzens'; a suitable match for the duke's son.
Not long after their engagement, a disease started plaguing Folsense. It was originally Sophia's intention to stay with Anton, but she discovered she was pregnant. So, keeping it a secret from Anton, she fled Folsense, fearing for their child's safety.
She founded the village of Dropstone, and had a girl (who eventually married Mr. Anderson and had Katia), living there for about forty-nine years, before passing away a year before the events of Diabolical Box.
Towards the end of Diabolical Box, Anton retrieves Sophia's letter from the Elysian Box.
"My dear Anton,
Are you well? I received your letter. Though I'd like nothing more than to see you again, I'm afraid I no longer have the strength to do so. You don't know how many times I've thought about you over the years. I often wonder if you hate me for what I did. Do you?
When I decided to leave, I was carrying our child. I couldn't bear exposing that tiny life to such danger. I knew your father's position, and understood you didn't have the option to leave with me. Even though I did the only thing I could, I'll always regret leaving you that way.
But there's one bright spot in this sad story, and that is our lovely granddaughter Katia. My departure all those years ago has given you the chance to meet. Katia's mother died shortly after she was born, but Katia grew up strong and sweet just the same. She reminds me of you every time she smiles. With her around, I could never forget about you, even if I wanted to.
You've been in my thoughts since the day we parted. And now, though my time here is drawing to a close, I like to think we'll meet again on the other side. The thought of seeing your face warms my heart. Be well and be happy, my dear Anton.
Goodbye, but just for now.
After reading this letter, Anton, with tears in his eyes, said that he wanted to be with Sophia, but before he did that, he needed to get to know someone else, first: Katia. He then vowed to spend his last years with her.
Anton brought Sophia a necklace that she is seen wearing as a young woman. A picture in Sophia's letter shows that she passed it down to Katia before her death, which is the reason Katia wears it in the game.
She and her granddaughter are so alike that when Anton first meets Katia, he mistakes her for Sophia.
Sophia shares the same voice actor as Katia in Akuma no Hako Lit.
Sophia was Katia's grandmother and Anton's former fiancée. In order to protect the child growing inside her, she left behind her life in Folsense to start fresh in the fledgling village of Dropstone. Kind and honest, she was loved by all.