The etiquettes in countries around the world are quite different. There are a variety of etiquettes in Japan, however, some of them provoke foreigners to think “why is it the case”. Hence, I will introduce 5 typical inconceivable etiquettes summarized from the internet.
1. Eat when walking
Many foreigners who have been living in Japan for years claimed that it would attract astonished eyes if you eat food when you walk on the street. Some even claimed that such behavior is banned. In some other countries, though, this behavior is not appropriate either, it is not as strict as in Japan. However, it doesn’t include the occasions such as food festival, food area in the tourist attractions.
2. Blow nose in public
Blowing nose in public with a big noise is not appropriate behavior in Japan, which is unbelievable for some foreigners. In contrast, sniffing is a disgusting behavior in foreign countries. Some would say it’s more appropriate to cleaning the nose if you suffer from sniffing.
3. Season sense of attire
For some foreigners, the dress code in Japan is a little complicated because it requires people to follow the season. My American friend told me a story before. Once he had been told that he needs to wear something with the long sleeve in his workplace in November, though he still thought the weather was quite hot. He said it is strange for everyone to remain the same dress code for a particular period of time.
4. Kiss in public
Kissing in public is kind of a taboo in Japan, while it’s normal in foreign countries. So try not to do so no matter how much you love each other. 
🙂
5. No rice + soy sauce
It’s not good for your health.