The reasoning for the general sense of dislike between the two nations isn't really for these pages (look up the Senkaku Islands or Japan's rule of China in World War II if you want a primer), but its effect on their respective populace and their car-buying habits is right in our wheelhouse.
This news of a Chinese teen running away from home because her parents were planning to buy a Honda is one of a number of auto-related examples of how tense Sino-Japanese relations are. The 14-year-old girl felt that her parents' purchase of a Japanese car would be "helping the enemy with money from our own pockets," according to a recent story posted on the website RocketNews24. The girl left for three days until her parents finally relented and agreed not to buy the car.
According to the RocketNews24, Chinese commenters are supportive of the girl's nationalism, with some continuing to support a boycott of Japanese products in the world's most heavily populated country.