Authorities are moving to crack down on laughing gas (nitrous oxide) as a recreational drug because it is becoming easier to obtain through online sales of bicycle tire inflators, which normally use carbon dioxide.

The product in question, called Sivagus, was being sold in silver canisters about 5-cm long by a retail website in London in mid-November that described it in Japanese as a "refill device for bicycle tires." A set of five costs ¥5,000.

The website of the retailer, which specializes in offering legal highs, goes out of its way to explain that "the product contains absolutely no substances that have been banned in Japan."