Obviously much of Japanese culture has Chinese inspirations. Even the Romance of the Three Kingdoms was read often in Japan. However, I never seem to hear of any Chinese culture that was inspired by Japan. What are, if any, examples of Chinese culture that originally were from Japan?
While I can't speak for concrete examples of material culture, there are many such examples in the sciences, and other intellectual developments.
As Korea played the role as a transmission point of Chinese culture (or at least the peninsula's version of it), Japan did likewise in the opposite direction. Many words in the sciences, humanities, and law come from new Chinese character compound words created by the Japanese.
Examples would be words like '電話' (phone [E], jeonhwa [K], dianhua [C], denwa [J], '物理學' (physics [E], mullihak [K], wulixue [C], butsurigaku [J]) and a plethora of others were adopted enthusiastically. The concept of nation/ethnic group '民族' (ethnic group/nation/'folk' [E], minjok [K], minzu [C], minzoku [J] are from the word 'volk', a German word, a word tinged with blood-based ties. Another legacy would be the idea of a post-Westphalian international law in East Asia. The very idea of sovereignty and the nation-state did not come out of the ether, but from the archipelago. You can see more examples on [https://en.wikipedia.org/wiki/Sino-Japanese_vocabulary#Words_.27made_in_Japan.27] in the 'Words made in Japan' section.
So-called 'Dutch learning' aka Western education in Japan [~17th-mid 18th centuries] was integral for what is today modern East Asia. Furthermore, many communists, and anarchists found their first dose of it in Japan while studying abroad, specifically the Shanghai Communist group.