Just before the stores open in Tokyo's Akihabara electronics district, buses pull up, unleashing Chinese tourists and their credit cards to snap up televisions, rice cookers and other gadgets. Walk into any department store and there they are, buying mascara, T-shirts and other merchandise.

China's infatuation with Japanese products is now discovering a new source of satisfaction: the internet. And Amazon.co.jp is responding.

On June 30, the web retailer quietly rolled out a Chinese-language version of its shopping site in Japan, along with new, reduced shipping rates to mainland homes and businesses. It's another example of how Amazon.com Inc. is evolving in Asia to open up new streams of revenue and make up for the lack of a bigger presence in China, where Alibaba Group Holding Ltd. dominates. Underscoring that potential, e-commerce demand from China to Japan is projected to almost triple to ¥2.34 trillion ($22.5 billion) in 2019, according to the Ministry of Economy, Trade and Industry.