Daimokuko is a ko (meeting to lecture Buddhist scriptures) composed by followers of Hokke sects.
It is also referred as Jusannichiko (lecture of Buddhist scriptures, composed by congregation of Hokke sect) because it was held before and after 13th day every month, having to do with the day when Nichiren, founder of the sect, died.
It is said that it was aimed to confirm the creed Nichiren advocated and relationship among followers by chanting together 'Namu Myoho Renge-kyo Sutra' (Devotion to the Law of Hokekyo (the Lotus Sutra), daimoku (Nichiren chant) of Hokekyo.
It has been known since the late Kamakura period, and it was also valued as a ritual for ikka-ichizoku rentai (solidarity of one family and one clan), because at an early stage participation in the ritual based on blood relationship was highly important. However, in the late medieval period it was transformed into a ceremony to tighten important connection of a regional community, and at the same time it was changed into a systematic organization to support the whole sect both in religion and economy such as facilitating to connect with daimokuko of peripheral regions and assisting rites and festivals and other activities not only of the main temple but also monryu (school of a sect) of the temples to which followers belong.