It makes for a fun bridging the gap cultural experience when talking to Chinese people about the Chinese idioms you learn in Japanese class. Even the pronunciation is so similar (I mean, of course it is, duh).

My favorite one is 吴越同舟 or 呉越同舟 (Wú Yuè tóng zhōu) meaning people of different backgrounds finding themselves having to work together.

https://www.zdic.net/hans/%E5%90%B4%E8%B6%8A%E5%90%8C%E8%88%...

https://jisho.org/word/%E5%91%89%E8%B6%8A%E5%90%8C%E8%88%9F

If only the two countries were as close diplomatically as they are in their shared culture.

It's indeed a regrettable circumstance that the diplomatic ties between the two countries don't reflect their cultural similarities. My parents, who are Chinese and in their 60s, managed to travel around Japan without knowing Japanese or English. They successfully took trains, hailed taxis, and communicated with locals using just a pen and paper, ultimately enjoying their trip.

I'm sure they have Chinese around other places, but one thing I've noticed around train stations in Tokyo is that for the major announcements they are read out in Japanese, English, and Chinese. Hopefully those announcements were something that helped them on their journey.

And Russian and Ukraine, presently superlatively so.

An excellent book on yojijukugo is "Kanji Idoims." from the "Power Japanese" series:

https://openlibrary.org/works/OL27733147W/Kanji_idioms?editi...