Daughter of Emperor Oshiro. Records from her lifetime such as the Emperor's Servant's Journal (dated 1429) suggest that she was working on a project to stop the spread of the unbound MajiMonsters that threatened Rathana. Later accounts (Journal of 3 Trapped Maji dated 1432) have her working with Captain Stancliff Preston, Mahavir Burman, and her sister Akari Oshiro to stop an unnamed calamity at the height of what later became known as The Fall of the Maji. Whether this was a continuation of the plan she was working on years earlier is unclear. Apparently either the weight of her failure to stop the spread of wild MajiMonsters, or the loss of many of her peers during the Fall of the Maji, caused Kasumi to become a recluse in the following years. There is no mention of her again in any documents until the date of her death in 1450, when her former friend Captain Preston happened upon a sick and dying Kasumi. He records the encounter in his memoir The Tales of Captain Preston:
As I took shelter for the night in a cave, I spied another denizen had made their camp here. And who should it be but dear Kasumi, who I had not seen in years! She was very sickly and weak and she could not even sit up without help. Her eyes were not like those of the Kasumi I knew, and upon recognizing me seized on me with a ferocity born out of hell. "You hid them. Give them back!" she crowed weakly at me. It hurt me to hear her still obsessed, still... corrupted. I held her as she raved, for deep down I believed the real Kasumi was still in there somewhere under all that madness. She knew she would not last the night, and asked me to bury her in the garden she once tended at the Emperor's Palace. I tried to explain that the capitol was not what it once was, that it was now The Scar of Rathana. She insisted still, and in the end I honored her last wish. I hope she is finally at peace.