League of Guardians Commitment to Protect All Sapient Species
When the League of Guardians was first created, it only served to protect the Yokai, since mortals had been the cause of most issues the League dealt with. Humans had hunted yokai and driven them from their homes. But after the Japan's population started to decline. Instead of yokai prospering with fewer mortals, the yokai population mirrored that of the mortals. Upon this discovery, the League decided to protect all sapients - mortal and immortal. Both needed to survive, for their fates were linked. An imbalance could prove disastrous for both groups.
Thus the most controversial document in the history of the organization was drafted. Soujoubou wrote and convinced the ruling council to sign 'League of Guardians Commitment to Protect All Sapient Species' pact, ensuring that all self-aware life would be protected. After that, the Task Force for the Discovery and Conservation of Semi-Sapient Slimes gained much traction. Slimes were added to the list of sapient beings and the wording of the document was expanded to include them. The League stores the pact in it's archives in Kyoto.