What is japanese straightening?

Thermal Conditioning. Japanese straightening is a form of thermal conditioning that is reported to permanently remove curls or wave from hair.
Hair straightening. http://nymag.com/nymetro/news/people/columns/intelligencer/9233/ this gives some information about it...
Japanese Straight. A hair system that originated in japan, utilizes heat, chemicals, and flat ironing to re-texture curly, frizzy hair bonds. The end result is permanent pin-straight hair.