Campervan parking

Hello,

I'm driving our rented campervan around mt.Fuji and Izu for 2 weeks.
*How can I know where I can park my campervan overnight?
(I mean the free car parking at some public parks, viewpoint, etc)

So-called "RV parks," "auto camping grounds," parking areas at "Michi no eki," and some areas in highway SA (service areas) and PA (parking areas).

Thanks AK,

What about the other parking such as parking near public parks, tourist attractions, etc?
Any Japanese sign telling about "not allow to park overnight"?

「Any Japanese sign telling about "not allow to park overnight"?」 - Yep, Japan has no parking sings and no parking areas. Did you think the country might not have those?

I actually mean "signage" in Japanese language saying about parking "overnight"

I don’t know how much authority this author has but she/he seems convinced that you can sleep nearly everywhere:

http://gocamperjapan.com/how-to-overnight-with-a-camper-in-japan/

From traveling through japan I would say that I did not see any signs about camping being prohibited at parking lots. Yes, there might be the odd parking lot where it is prohibited but it’s not something I remember seeing. (And I have been around Japan a lot, albeit by bicycle).

I would also ask the company where you rent, what their advise is.

Michi no eki are good places as well as you get some basic facilities.

Enjoy your ride through Japan!

Thanks so much BikeLike.
Have a nice bike trip in Japan :-)