Otsuka Seicha was founded in 1869 by Shinpei Otsuka, a samurai given land at Nissaka in Kakegawa when the feudal system was dissolved. The ground turned out to suit tea, and five generations later the family still works it.

Kakegawa is mountainous and cut through by rivers. Sea wind off the Pacific carries damp, mineral-rich air that hangs against the slopes as fog, which shades the plants without anyone covering them. Large differences between day and night temperature slow the growth down, and slow growth is what puts flavor in the leaf.

A quarter of the gardens here is grassland. Under the chagusaba method, more than three hundred grasses and herbs are cut, dried and laid between the tea rows as organic fertiliser. It feeds the soil, keeps the weeds down and supports the wildlife, and the region holds a GIAHS listing for it.

Otsuka began deep steaming in the 1950s, in the region where fukamushi started. Since 2015 their factory, warehouse and packing facility have been certified organic, along with a number of their gardens and contracted farms.