Chapter 141: Protector
Kūgo Ginjō's possession of Fullbring was not a secret.
It's a very novel power.
The 12th Division monitored him for a year with his permission, confirming that this power does not disrupt the balance of the three worlds. When a Hollow is destroyed by Fullbring, its spirit particles return to the Soul Society just as they would when a Shinigami eliminates it, rather than being completely annihilated.
So, although this power exists outside the control of the Gotei 13, since it doesn't disrupt the balance and Kūgo Ginjō is the only known user, it was decided, after some discussion, to maintain the current stance on Kūgo Ginjō without any changes.
Many people were interested in Fullbring.
But...
Few dared to express this interest, let alone take any action.
That Substitute Shinigami was brought to the Soul Society by Captain Uzumaki Naruto of the 7th Division.
Interactions with him were primarily mediated through Captain Uzumaki.