Dentsu, Japan’s largest ad agency, said it will team up with Nintendo to launch a video distribution service on the Wii. The two companies plan to offer programs created specifically for the service, a Dentsu representative said Thursday. By contrast, most online channels tend to carry existing TV shows and movies. According to the Nikkei business daily, the programs will focus on cartoons and other entertainment. Viewers will need to pay to see some of the programs, while others will be offered free of charge and accompanied by ads, the representative said. Nintendo had sold 34.6 million Wii consoles as of the end of September, far outselling Microsoft’s Xbox 360 and Sony’s PlayStation 3. Dentsu and Nintendo will launch the new service in Japan next year, while the timing for overseas sales has yet to be set, the Dentsu representative said.