Ramen is Chinese, the Japanese term comes from "la mien" in Chinese or pulled noodles. Alcoholic fermentation of rice spread to Japan from China, and sushi is likely of southeast Asian origin, with the first written record of sushi-like food from 4th century BCE in China, all of this according to Wikipedia. English Wikipedia does credit mochi being japanese, I'd be surprised if this is actually the case, I found a SCMP headline claiming mochi were introduced from China in 300BCE, pointing to Taiwan's "moâ chi" and Hong Kong's "log máih chih" type of rice snacks.

Most foods we attribute to Japanese culture are Chinese in origin.