Ofumi

From Miki Nakura:

Rennyo Shonin, in particular, struggled to convey the teachings of Shinran Shonin to the illiterate masses, and wrote "Ofumi" letters by breaking down the profound content without missing the essence. Therefore, "Ofumi" is essentially something to listen to, not read. Genza could not read or write, so he must have listened intently to Ofumi many times.