The Japanese culture puts a heavy emphasis on mindfulness towards the needs of the community rather than the individual. Within the culture, if somebody in the community say in school or at a workplace, makes a mess then people tend to see cleaning it up as a shared responsibility within the community. After all, it is a shared space.
The reason for the importance accorded to cleanliness is hard to pinpoint, though religion does play a part. Shintoism (Shinto: way of the Gods), which is the most prominent religion of Japan practised by nearly 80% of the population. Shintoism teaches that Evil is associated with dirtiness, good with cleanliness. According to Japanese adherents of Shintoism, the original creator was born in the sea; worshippers at Shinto shrines still wash their mouths out. For many, cleanliness is not next to godliness, but for the Japanese it is godliness.
Most have at least one bath a day; rare is the young woman who does not have at least two. Washing does not involve a superficial flick of the flannel, but a vigorous all-over scrub, often with an extremely rough nylon towel. With this extreme adherence to cleanliness, it comes as little surprise that Japan is home to more than 15,000 onsen — a term used to describe the bathing facilities and inns around the hot springs.
Like visiting a bar or pub with friends in the West is the norm, spending the weekend or a holiday with close friends or family at an onsen in the countryside is common.