It is illegal to have the same name in a Japanese restaurant. In Japan, the Trademark Law has strict regulations on the registration, use and protection of trademarks. If a restaurant's name is the same as that of another brand, it may involve trademark infringement issues. In addition, if the name is considered to be highly similar to the names of other brands, it may also be considered as unfair competition and violate the provisions of the Unfair Competition Prevention Act.