Japanese airlines' airsickness bags (
barf bags) are generally labeled "Waterproof Disposal Bag" in English and also sport several lines of
Japanese that can be literally translated to "Please use if your feelings are worsened."
Of the three major airlines in Japan, All Nippon Airways' barf bags are of the highest quality. They are colored a nice shade of cobalt blue that matches ANA's aircraft colors, and the bags themselves are quite resilient. Japan Air System's green barf bags are interesting because they have a perforated top that the passenger has to open before the bag can be used, which presumably makes the inside of the bag more sanitary but makes it less effective for someone who has to blow chunks of tekka maki in a hurry.
However, if you feel the urge to vomit on a Japanese airliner, it is probably best to sprint toward the nearest lavatory, as the other passengers will undoubtedly be disturbed by the sounds and smells of retching up gallons of Kirin Ichiban.
Update: http://member.nifty.ne.jp/ohayuni/geroe.htm ... someone else is interested in this area, too?