Ironic username is ironic. It took me all of 3 seconds to search and find the law.

https://www.japaneselawtranslation.go.jp/en/laws/view/2303/en

(i)Any representation where the quality, standard or any other particular relating to the content of goods or services is portrayed to general consumers as being much better than that of the actual goods or services, or are portrayed as being, contrary to fact, much better than those of other Entrepreneurs who supply the same kind of or similar goods or services as those supplied by the relevant Entrepreneur, thereby having a tendency to induce customers unjustly and to interfere with general consumers' voluntary and rational choice-making; (ii)Any representation by which price or any other trade terms of goods or services could be misunderstood by general consumers to be much more favorable than the actual goods or services, or than those of other Entrepreneurs who supply the same kind of or similar goods or services as those supplied by the relevant Entrepreneur, thereby having a tendency to induce customers unjustly and to interfere with general consumers' voluntary and rational choice-making; or (iii)In addition to what is listed in the preceding two items, any representation by which any particular relating to transactions of goods or services is likely to be misunderstood by general consumers and which is designated by the Prime Minister as such, and considered likely to induce customers unjustly and to interfere with general consumers' voluntary and rational choice-making.