Onmyoji Story from Another World

It tells the story of a young boy who was killed due to God's negligence and transferred to another world with his memories and a younger sister. When the young boy was 12 years old, a disaster occurred and everyone in the village died. Only he and his younger sister survived. They escaped disaster and were picked up by a lady when they were about to die. You asked them to go to a noble school, but they were bullied by their classmates. My brother accidentally met the Phoenix once, and what happened next? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.