The device known as shoyu-tai (or soy-sauce snapper in Japanese) was invented in 1954 by Teruo Watanabe, the founder of Osaka-based company Asahi Sogyo, according to a report from Japan’s Radio Kansai.
It was then common for glass and ceramic containers to be used but the advent of cheap industrial plastics allowed the creation of a small polyethylene container in the shape of a fish, officially named the “Lunch Charm”.
The invention quickly spread around Japan and eventually worldwide, and it is estimated that billions have been produced.
If my wife wasn’t soy intolerant I’d have a bottle of soy sauce in my fridge (her issues with soy mean I really only get east Asian food when going out) and if she liked fish I’d get takeout sushi sometimes. Though honestly if she liked fish and could eat soy sauce I’d’ve learned to make sushi by now, so maybe I’m not the default here