This technique was invented by Sōma Chinoike who studied an old veteran's juinjutsu seals during the earliest recorded history regarding Root; a ruthless and extreme group of black ops that operate, they were seal on certain body parts to ensure they don't spill the secret of their leader or mission. Applying this seal onto subjects within her cult as a safeguard in case they are captured or killed, the body is incinerated ensuring no one will be able to learn anything, The seal remains on the victim even if the caster dies.
The wearer that is branded with the hexagram seal "䷮" (kùn, Confining) that's surgically implanted within their internal organ (place on the heart or liver), those who tries to speak of any incriminating evidence related to Sōma Chinoike, is cornered or captured by the enemy the seal will activate instantly burning them from the inside out which can be activated by weaving the Rat sign, the seal that spontaneously release the "Flames of Purgatory" (煉獄の炎, Rengoku no Honō) will incinerate and burn the wearer to a charred corpse or burn and liquify the wearers insides killing them.