you take your shoes off when you go into anyone's house out of respect, and not dirtying their floor. There is usually a area you step up to. Leave your shoes in the lower part.
The main 2 religions are Shintoism and Buddhism, there are many temples and shrines that you can visit.
Onsen (hot spring communal baths) are part of the culture in japan, and are often part of favourite holiday destinations. usually split into mens and womens areas, you go naked, but wash all over first before joining a bath. They usually have different temperature waters, from super hot to cold, even medicated water for different kinds of healing. You'd often also get a massage after the bath. Bliss
(Never slept better)
When greeting people you bow rather than shake hands, but people there are used to westerners wanting to shake hands.
Kimonos are usually for special occasions only.
Full on kimonos, are super hard to move and breathe in.
Although most houses (at least in cities) don't have the sliding doors, many do have a washitsu (Tatami mat room), where the flooring is woven straw mats. (smells great)
The language has several politeness levels of speech, and shares the meaning of the chinese characters (but not the pronounciation)
They take great pride in fresh, healthy ingredients in their food, and you can really taste the difference (they also live to oldest age on earth on average).