The Japanese are a scrupulously clean people and Japan is a scrupulously clean country. Cleanliness and tidiness are a part of Japanese culture and tradition going back centuries and centuries.
When visiting Japan, one will immediately notice the extreme lack of litter nearly everywhere. Public transportation vehicles and stations are virtually spotless and never neglected. Japanese homes (both traditional and modern) are also nearly always extremely clean, neat and tide, When entering a Japanese house, one immediately takes off one's shoes and is often asked to wear slippers which are often at the entrance for visitors to wear. Housekeeping and picking up after oneself is common and encouraged. This is not only applicable to home, but also to schools, as children are taught and practice cleaning up in school.
And it is not just material cleanliness. Personal hygiene is a huge part of traditional and modern Japanese culture. This too has been passed down for centuries. Consideration for others is largely a part of this, as wearing of a mask when one is sick even with a common cold is practiced throughout Japan and is not a product of COVID-19 as it has become in most Western countries.
Considering all of the aforementioned, it is only natural that cleanliness and tidiness are a must in the dojo. Soji (cleaning) is seen as a part of being a student. For example, cleaning the dojo floor is done after each class without fail. Every student, no matter what rank, participates in this very important ritual. Using damp and clean towels students will lineup side by side and push their towels across the floor until the entire floor is completely clean. Afterward, the towels are wrung out, rinsed, usually hung up on a rack and the lower rank students most often will dump the water from the bucket if a bucket is used.
This regular ritual is seen as a part of training and also is to instill humility, cooperation, group spirit and fellowship among all. It is not a punishment, as many may think. And it is to maintain cleanliness and hygiene.
Cleaning the floor and cleaning the dojo also gives and shows respect to the instructor and/or instructors of the dojo instill a clean and professional presentation for all who may visit the dojo for training and also those consider joining the dojo.
This exact same ritual is practiced by most traditional dojo (of any Japanese martial art) outside of Japan.
"Why not just use a mop and bucket to clean the floor and hire a janitor to come in and clean the dojo?" you may ask. Once again, it is seen as a part of training and also is to instill humility, cooperation, group spirit and fellowship among all. Some Westerners resist this ritual citing that they are not attending the dojo to clean the premises and even have gone to state that they are not paying their training fees to clean a floor and the premises. This poor attitude goes completely against the principles of Karate-Do and all other Japanese martial arts.
And it is not just the floor. Quite often times areas of the dojo such as restrooms and dressing rooms will be given attention, though not as often as the floor. Most dojo clean the entire dojo thoroughly at the end of the year after the final training session. Or sometimes the final training session of the year IS exclusively the entire cleaning of the dojo thoroughly.
All of this practice of cleanliness and hygiene is not just due to the outbreak of COVID-19 as it has become in most Western countries. It has been passed down for centuries.