As I wrote before, most of the small Chinese restaurants in Japan are not owned or run by Chinese but by Japanese who were born and raised in Japan. These Japanese do not have even an ancestors from China.
Chinese cuisine is very popular in Japan but many recipes are adjusted to Japanese styles.
One of the samples are ebi chili. Ebi chili is a stir fried shrimps in chili sauce. Ebi means shrimp in Japanese. It is one of the most popular Japanese style Chinese dish in Japan which you can find at local Chinese restaurants throughout the country.
It is in a chili sauce but it is not so hot as you expect. The taste is quite mild due to ketchup is used.