booking ahead

Hello,

I am traveling to japan from mid march-early April.

I have already booked my accommodations and my JR rail pass. However, I was wondering if I need to book anything in advance prior to leaving. Would I need to also book certain onsens in advance?

We are going to Tokyo, Kyoto, Osaka and Hiroshima, and looking to do daytrips in Hakone, Nara, Mt Koya and Kobe.

Any suggestion would be appreciated, thank you!

Not sure what you mean by "booking onsen"... if you're staying at a ryokan overnight, then I would definitely book in advance. If you mean you're making a day trip somewhere and want to use the onsen for an hour or two wherever you're going, then there's no need unless you are wanting a private room, in which case if you're able to book, you might as well.