Tsuneo enjoys being the head of his clan. He's allowed to do whatever he wants which includes coming and going to the human realm freely.

That's where the mischievous kitsune found a little, quite powerful human he could play with. He was just going to siphon a bit of power from her but somehow got roped into a contract with her.

This pesky human took away his freedom. She seems completely oblivious to the power she has over him. When the contract breaks...He decides to stay willingly...