Monochrome Factor - Shadows from the past

Akira Nikaido has become the light king. Shirogane is by his side. Together they are in the shadow world. Kengo Asamura, Akira's and Aya's best friend was killed by Homurabi, a shadow king. Aya was sent to the real world and her memory was erased. She is working in a large business firm.
Years passed and Aya got married to one of her colleagues. She has a daughter named Mimi. The girl, who is now 26 years old is pursuing a career. After repeated failures at interviews, one institution finally appoints her. That weekend, she visits her grandpa's house, .the Suzuno family house and her grandfather gives her a mysterious family treasure. That leads to a fateful meeting with her destiny.
What could it be?
This is a fanfiction based on the manga Monochrome Factor by Kairi Sorano. This story continues from where the actual manga ended so if you haven't read the manga you wouldn't be able to follow.