Kompu Gacha means "Complete Collection", meaning it will take several virtual items or characters to earn the special grand prize. Kompu Gacha was banned back in May 2012 and there were several reasons why it was banned: cases of consumers (Specifically kids under age of 18) spending thousands of dollars in less than a week and violation to Japan's fair trade act.

Japan has it's own Consumer Affairs Agency (CAAJ) and Fair trade Commission (JFTC) which is equivalent or similar US's Trade Commission. "Kompu Gacha" violated Japan's Fair trade Act, Article 4 (ii)

Article 4

No entrepreneur shall make such representation as provided for in any one of the following items in connection with transactions of goods or services which he supplies:

(ii) Any representation by which price or any other trade terms of goods or services will be misunderstood by general consumers to be much more favorable to the general consumers than the actual one or than those of other entrepreneurs who supply the same kind of or similar goods or services as those supplied by the entrepreneur concerned, and thereby which tends to induce customers unjustly and to interfere with general consumers' voluntary and rational choice-making; or

Japan: Laws against unjustifiable premiums and misleading representation

Here's Example of Kompu Gacha:

kompu gacha example

US Equivalent - FTC Act Section 5: Unfair or Deceptive Acts or Practices

This is closest section which is similar to Japan's Fair Trade Act mentioned.

Any information I missed please let me know..