It’s common that Japanese people wear five toed sock. Those socks’ purpose is not to be fashionable. Actually those make toes healthy and clean.
First of all, by wearing five toed socks, toes are able to move better than wearing regular socks. Because of it, muscles bear the body become strong which makes a blood circulation better.
Second, do you know toes sweat although you don’t feel it? And that is why your shoes become smelly eventually if you keep wearing same shoes often. By wearing five toed socks, each toe’s sweat is absorbed by socks which keep your toes clean all the time when you are wearing them.
Honestly it’s takes time and not easy to wear/take off five toed socks. But their functions are much better than regular socks.