Having lived abroad (in Japan for a year) and taken international-awareness classes, I’d advise this:
If someone’s going to Japan (or any other country) for short-term visiting then it’s ok not to know tons about the country BUT looking up basic etiquette is always a good idea. Don’t worry too much, just show that you’ve made some effort and it will be appreciated. I do think it’s a bad idea to not know ANY country-specific etiquette–that sends the message that the visitor cares only for their personal experience rather than interactions with natives. Foreigners in Japan are stereotyped as loud and gross, and by simply avoiding eating in public (which is considered rude in Japan–something you wouldn’t know by instict and thus worth knowing before you go) and being loud in public places you can help fight those stereotypes and help everyone have a more enjoyable experience.
Longterm visitors should definitely learn about the etiquette since their interactions with natives will be much more frequent and vital for successful (aka less-painful)immersion.

What about… No. I will behave the way I always behave. The japanese may demonstrate their politeness by abiding to the international rules of etiquette. Like not bowing to anyone and being polite, but not being subservant or rude to the wait staff.