Of course, thanks to their sordid past, Japan does not enjoy good relations with many Asian countries.
My experience in Taiwan over some five visits of a week or longer each led me to believe that Japanese are welcome in Taiwan, and one certainly sees a myriad of Japanese products to include autos, as well as some Taiwanese products such as saki which are the residue of their colonial days. Japanese investment is certainly welcome.
As for Vietnam, Japanese products enjoy a high reputation among the public, especially in motorcycles (Honda, Yamaha, Kawasaki) and watches (Seiko), followed by Korean products. And Japanese are certainly welcome for tourism and investment. I dimly remember news coverage of a former Japanese who joined the Viet Minh after WWII, and even fought the Americans. IIRC he was returning for a visit and may have had a Vietnamese wife.
Other than China and North Korea, I can't think of any East or Southeast Asian countries who do not enjoy good relations with Japan, and the South Koreans certainly welcome Japanese tourists. As for Japan itself, Korean soap operas and Historical sagas are quite popular on Japanese television and generate no small level of Japanese tourism into Korea. In seven years of living in Seoul, I cannot ever remember going into the Namdaemun market and not seeing long lines of Japanese tourists led by their (tourist company) flag waving guides. (Of course, they did not take them anywhere near universities during Dokto Island demonstrations.)