Jujutsu kaisen:The tale of Ryomen Sukuna.

Imperial Prince Oshikuma (later became Sukuna Ryomen the king of curses) hid himself in the depts of the Mino province accompanied by his army and followers; where he continued training to become stronger and get his revenge on the empress and her son whom killed his older brother that he looked up to. that is where he met a certain person who changed the way he viewed the world, that person for him was the light that lit up his life again with a glimpse of happiness and love. He promised himself to protect that person with all of what he got in his power.
This is the tale of a love story between a cursed sorcerer prince and a woman who is trying to protect her clan while learning jujutsu.