JR Seishun 18 Kippu, highway busses or?

Hi

I'm doing some backpacking in Japan in august/september, and my travel plans at the moment are:
(1. take the ferry from Busan, South Korea to Fukuoka)
2. go from Fukuoka to Hiroshima
3. from Hiroshima to Osaka
4. from Osaka to Kyoto
5. from Kyoto to Tokyo

I have around 3 weeks in Japan and would like to know the cheapest way of this travel?
It looks like "JR Seishun 18 Kippu" are the cheapest?
Or maybe the highway busses (looks like it would be max 19.500 yen)?

Besides that I'd like to know if you would recommend a Japanese Encephalitis vaccination?

Kind regards
Helle

Seishun 18 kippu is cheap and convenient, but only downside is long travelling time and can sometimes be difficult to know where to change trains. Good thing is that if you get too tired of sitting in the train, you can always get out on a random station and check out a local area.
But if you wanna be more relaxed about reaching your goal in a fixed time without worrying about too much, then taking day or nighttime buses is probably the best.

btw, are you danish?

No, you do not need a Japanese encephalitis vaccination. The word "Japanese" happens to be in the name of the disease for historical reasons, but that does not mean it is common here now. I have lived in Japan for 11 years and have never heard of anyone who has caught it.

@ Sira: Thanks, I know Japanese E, has nothing to do with geography, he ;) But it looks like the mosquitoes are present in Japan and South Korea in July-September where I am in those countries, so I was a bit worried.

@Andy: Thanks to you too. Do you know if it'll take longer to take the trains with Seishun 18 kippu than the highway busses?
And yes I'm Danish :)