After Hijin's death, he traveled back to the Hunter and wrote a letter to Byakuya Kuchiki that was destined to be unsendable.
Note: Adhere to the White King's way, and provide an explanation for Hijin's abandonment of Rukia. The author believes that Byakuya Kuchiki will not violate the education he has received since birth for her before recognizing Hijin's true nature.
Ps: I am not a research party, please be merciful.