It is cultivated and used in cooking in Japan and Korea.
When the seaweed is harvested, it is washed in salt water, then laid out to dry in the sun with charcoal sprinkled over it. The charcoal neutralizes an enzyme in the seaweed, and by doing so, helps to preserve the seaweed.
Ito Wakame harvested in the spring is considered the most desirable.
Ito Wakame will appear dark brown in packages when dried, but regains some of its green again when soaked.
Wakame made its way to New Zealand waters as early as 1987, where it is regarded as a “pest” infesting local waters. 
Ito Wakame can be used in soup or salads.
Before using, wash under running water, and soak for half an hour. Cut off any tough ribs remaining.
The harvesting process dates to somewhere between the sixteen and eighteen hundreds.
A patent seems to have been granted in 2002 for a somewhat modified process: “This charcoal dried seaweed is produced by a step 1 of harvesting raw algal seaweed, a step 2 of smearing the surface of the raw algal seaweed with dust charcoal before drying the raw algal seaweed and a step 3 of drying the seaweed smeared with the dust charcoal. The charcoal dried thinly cut seaweed is produced by a step 5 of washing the charcoal dried seaweed, a step 6 of removing the central core of the washed charcoal dried seaweed and a step 7 of drying the seaweed freed of the central core.” 
 Forrest, Barrie M. Managing Risks from Invasive Marine Species. PhD Thesis. Victoria University of Wellington. 2007.
 Japanese Patent Office. Application No: 2000-217839 / 18 July 2000. Document No: 2002-034520. Charcoal dried seaweed and charcoal dried thinly cut seaweed or method for producing the same. Retrieved July 2009 from http://www.ipexl.com/patents/en/JPO/Uzushio_Shokuhin:Kk/Goto_Hiroki/2002ZZDASHZZ034520.html.
Tokushima Tourism Association. Tokushima Prefecture: Gifts from the Mild Climate. Kansai International Public Relations Promotion Office. 2002. Retrieved November 2007 from http://www.kippo.or.jp/culture_e/syoku/umiyama/tokushima01.html