Since Tokyo is in the very far East of Asia the only countries easy to get to is Korea and the PRC. Russia is right there but I've never been and don't know what restrictions there are in getting there. Hong Kong is about a 4 hour flight and Taiwan not much closer. There is a lot to see in Japan itself though and you could easily fill two weeks just in Japan. If you friend is in Hokkaido, the main northern island, that isn't that close to Tokyo. If you're pressed for time might want to fly to Sapporo instead of taking a train.
When my friends did the 6 countries this was their main 3 segment trip on united. Houston to Tokyo Tokyo to Hong Kong Kuala Lumpur to Houston. The rest they booked other flights. I could do something similar. Houston to Tokyo Tokyo to Taipei Taipei to Hong Kong Hong Kong to Houston. Geographically grouping Thailand, Cambodia, Vietnam, Malaysia and Singapore makes sense. It's a lot of countries. lol. :grin:
The route I took last time I went (only been to Asia twice) was Houston to Beijing (long layover in Shanghai walked around for about 5 hours) to Bangkok to Tokyo to Hong Kong/Macau. This was done over I think 20 days. I was totally spent by the time I made it to Hong Kong. Although there was a lot of partying/drinking involved with people I met. And I had to spend the night at the airport in Tokyo because my flight left too early to use the train and a taxi was quoted at more than $300.
