According to Kojirou, it's given in folklore that of the deceased that enter unto the court of the Enma in the Japanese Underworld, those guilty of the sin of dishonesty are "parted with their tongues."
He elaborates that the Lord Enma is equivalent to the figure in Buddhist mythology known as the Yamaten (
夜摩天, yamaten), "the first among the dead" (最初の死者, saisho no shisha), who by the will of the Buddha is vested with the duty of the Underworld's administration. The ten sparrows that act as the top officers under Beni-Enma within the Inn's management structure are named after "the Kings of the Ten Courts" (十王, jyuu-ou; the ten sparrows that appear in Beni-Enma's NP animation) that preside over the judgment of the deceased.
One amongst the sparrows gives that Beni-Enma was originally a human -- a kamuro (禿), or a girl-child sold unto the red light district that would prospectively be trained as an
oiran. Running away from captivity, she ventured unto a Mayoiga (
迷い家) -- an illusory house that entraps wanderers in the deep mountains -- and therein lost her life. However, before her death, she somehow quelled the Mayoiga, and was therefore absolved of sin when passing unto the Underworld. Thereafter, she served as an assistant to the
Datsue-ba (奪衣婆), on the banks of the
Sanzu (三途の川, sanzu no kawa) -- the Oni responsible for stripping the deceased of their clothing; who had in fact inhabited the Underworld since before the Enma arrived; who he'd taken as his wife.
The sparrows elaborate that the Datsue-ba was the miserly sort, somewhat alike to those who had abused Beni-Enma in life. Rather than paying Beni-Enma, she reasoned that if Beni-Enma would become as her daughter, there wasn't any need to pay her for her services. However, because of Beni-Enma's perseverance under such conditions, the Enma elected to take Beni-Enma under his wing as a formal ward -- making true on Datsue-ba's promise. Thus, the iaijutsu practiced by Beni-Enma is the iai of the Enma himself; and Beni-Enma's title of Shita-kiri (舌斬り, shita-kiri), "the Tongue-Cutter," isn't merely for show.
After becoming a ward of the Enma, Beni-Enma was vested with the administration of the Mayoiga, and thereon opened the Enma-Tei to the Surface. The sparrow elaborates that the purpose of the Enma-Tei is to grant healing to those Gods that have suffered injury, and to save humans who have lost themselves in the mountains.
Kojirou hypothesizes that would be the justification for the Inn of the Sparrows (雀のお宿, suzume no oyado) that appears in the folktale of the
Tongue-Cut Sparrow -- but the sparrow states that he cannot confirm this with any certainty, as the continuity of time in the Underworld and upon the Surface do not match.
According to Mashu, the folktale of the Mayoiga gives that it's a deserted mansion in the depths of the wilderness, within which those who are lost discover a grand meal prepared within the dining area, and treasures untold. If they partake of the food, or seek to acquire the treasure for themselves, they are no longer capable of finding the exit, and thereafter meet their deaths; but if, in the opposite case, the wanderer controls their desires and keeps their hands to themselves, they will upon returning to the World of Man find happiness. The house itself is considered a kaii (怪異) that tests the desires of Man -- similar to the judgement of the Enma.
Mashu observes that the Enma-Tei more closely resembles the Inn of the Sparrows from the folktale, rather than the Mayoiga; as rather than testing the desires of man, it in the first place draws unto its premises only those who are kind of heart. The sparrow clarifies that this is the form that the Mayoiga has taken under the administration of Beni-Enma; the original form of "the kaii that saves those wanderers that lose themselves within the mountains" spoken of in the
Uji Shuui Monogatari (宇治拾遺物語) -- which Kojirou compares to the Japanese version of Nursery Rhyme.
In any case, Mashu gives that Beni-Enma isn't a personage who became a Hero in life; but one that became a Hero in death.
EDIT:
"Sasaki is omnipresent. It's said that he exists everywhere and nowhere."