Inka means to allow, or to recognise. This word is used when a priest give the certificate to his disciple after the disciple would master the Buddhism. This word is also used in Bujyutsu or art.
This certificate was given to Dainen priest, the founder of Koujyouji, in December 12th, Kenbu 4(1337) from his teacher, Jikusen Bonsen.
It is 33cm long and 95cm wide.
Bonsen was the Chinese priest. He moved to Japan after he learnt Buddhism. The Houjyo family, the regency of Kamakura government, welcomed him and allow to stay in Jyomyouji in Kamakura. Takauji Ashikaga also became a believer of him.
The disciple, Dainen priest, learnt the philosophy of Buddhism while Bonsen stayed in Jyoumyouji and it was recognised that he have mastered Buddhism. It was written at the begging of this certificate. and it also says that it is Hounen who would burn Bonsen's incense.
There are many priests who would come from China and Bonsen was one of great priests. He was also good at writing and one of his writings is registered as the cultural property and 5 of them are registered as National Cultural Property.
Explanation 
Koujyouji
