Konbu

[T]he productions of Jeso, in particular, are as follows: konbu, or sea-cabbage, birds of prey for hawking, whales and other sea-fish, skins of otters, beavers, seals, and stags, castoreum, gold, silver, adamantine spar.

The Japanese tangles are called konbu and represent important genera of seaweeds which have been used as food since ancient times. […] Konbu is harvested mainly in the various coastal areas of Hokkaido during the period from the last ten days of May to the end of September. Konbu is mostly dried in the sun soon after harvest, but sometime^([sic]) in a hot-air drier depending on weather.