The leaves used for this tea come from trees that are over a hundred years old. Contrary to normal Sencha, where the leaves are being processed immediately after the plucking, the leaves of this tea have been left over night before being processed. This gives the tea a particular taste that is typical for this hilly region.

Zairai is the original Japanese tea variety, with its roots in China. Just like the local varieties in China, the Zairai have been reproduced through seeds, hence their genetic material is heterogeneous, contrary to the contemporary reproduction through cuttings.