Japan protests dessert to be served to North Korean leader Kim Jong Un

The cake is planned to have a picture of a unified Korean peninsula.

After South Korea announced it would dish out a mango mousse cake decorated with a garnish showing the shape of a unified Korean peninsula, Japan objected to the map’s inclusion of disputed islands.

Japan filed a protest on Tuesday with South Korea, a spokesperson for Japan’s Ministry of Foreign Affairs, Natsuko Sakata, told ABC News.

The disputed island grouping is located in the sea between South Korea and Japan; they’re known in South Korea as Dokdo and in Japan as Takeshima. South Korea controls the islands, but Japan also claims them. North Korea has said it considers them Korean.

A map of a unified Korea that features the disputed islands will also appear on chairs that will be used by Kim and South Korea’s president, Moon Jae-in.

"Nations have no other choice but to react this way because it is an ongoing territorial dispute," David Satterwhite, an expert on Korean politics at Temple University Japan, in Tokyo, told ABC News. "Japan has to say, 'Wait a minute, that’s Japanese territory.'"

ABC News' Anthony Trotter reported from Tokyo.