Kechimyaku-sojo (also referred as kechimyaku-sosho) or blood inheritance is a metaphor that is used to describe the inheritance of teachings (Buddhism) from a mentor to a pupil, taking the blood flow as an analogy.
The teachings in kechimyaku-sojo consist of the principal object of worship, doctrine, religious precepts, documents describing the esoteric techniques and secrets, and treasures, which are all given from a mentor and, therefore, are 'the things that need to be inherited by a person who will become a mentor in the next generation.'
Generally, everything is transmitted behind closed doors. Its meaning can vary from when it is looked at as a mere inheritance, to when it is looked at as secrets being handed down from father to son.
Jodo Shinshu (the True Pure Land Sect of Buddhism)
It is called Dento-sosho (the light inheritance) in the Jodo Shinshu. In the Hongan-ji School and Otani School of the Jodo Shinshu, the word particularly refers to the hand-over of the position of the chief of the school to a descendant of Shinran.
It is called Hoshi in the Zen Sect, in which they claim that it was Daruma who was the twenty-eighth founder of fuhozo (those who, after Shakyamuni Buddha's death, successively inherited the lineage of his teachings and propagated them in India) that succeeded the Kyogai betsuden teaching (transmission of spiritual awakening without words or characters, but in a heart-to-heart way) from Shakamuni to Makakasho, through intuitive discernment from generation to generation. It can be proven by the receipt of the robes and bowls of the predecessors up to Eno, the sixth founder of the Zen Sect.
Nichiren Sho Sect
Please refer to the article of Kechimyaku-sojo (Nichiren Sho Sect) for Kechimyaku-sojo in the Nichiren Sho Sect.
There are sects that do not use the term Kechimyaku-sojo or do not have a concept similar to Kechimyaku-sojo.
Kechimyaku at Zenko-ji Temple
Zenko-ji Temple in Nagano Prefecture regards the kechimyaku as a certification to be reborn in heaven.
Anyone who pays a fee at the place to provide the kechimyaku can be given 'the kechimyaku stamp ensuring the road to heaven' on its forehead. It seems that this ritual had already became popular in the Edo period, and was used as material for rakugo (a traditional comic monologue), titled "Okechimyaku."