Suggestion for stop between Osaka and Tokyo

Are you aware that Himeji Castle is under scaffolding? You can still enter it and see the construction works, but won't have that picture postcard view of the main keep.

Is Nagoya worth a visit?
Depends what you like. Some suggestions which are slightly off the direct shinkansen route:

-Ise Shrines+Meoto Iwa
-Tsumago+Magome
-Hakone
-Kawaguchiko
-Kamakura+Yokohama (perhaps better as daytrip from Tokyo)

I really appreciate your advice.
You have helped me several times now,and you always have good advice.
Thank you!

I did not know about Himeji. So I guess, I won't go there.:-(

I considered Ise, but was worried it would mean too much travel for a one-day stay.

As for Ise, we had a similar itinerary as yours. After a full day of sightseeing in Kyoto we went to Ise in the evening. We stayed at Hoshidekan which I would recommend if you are looking for a budget ryokan option.

Next day we saw Kawasaki in the morning (ca. 9am to 10am), late breakfast, then the two Ise Shrines (ca. 11am to 1pm), Oharaimachi (ca. 1:30 to 2pm), Mikimoto Pearl Island (ca. 2:30 to 4pm; which I would not recommend); late lunch and Meoto Iwa (around sunset, i.e. 6pm) before taking one of the last train connections home to near Tokyo (later options would have existed if we were to go to central Tokyo).

Generally a very enjoyable day, and we even happened to see the then to-be prime minister Yukio Hatoyama at the Ise Shrines!

If you can leave Osaka in the evening before, a similar itinerary should be certainly possible. Even if you can leave only on the same day, the main parts should be possible if you start early. As you can see from above timings we did not get up extremely early on that day.

Korea will be very much colder than Japan in December. Stock up on warm & cheaper than Japan clothing in Busan. What about Miyajima and / or Hakone or Kawaguchiko (Fuji Go Ko) for views of a hopefully snow-capped Fuji? I liked Nagoya. Under rated & not swarming with tourists. The Mode Hal Issen or spiral building was eye-catching:

http://www.trekearth.com/members/ChrisJ/photos/Asia/Japan/Chubu/Aichi/

Osu district of Nagoya for markets & temples. Some pics by a respected photographer friend: http://www.norbertwoehnl.com/en/people/nagoya-osu/

The bullet trains make travel between Tokyo Nagoya & Osaka VERY fast safe & easy.

What is your full itinerary including dates?

Will you have an active JR Pass?

Do you plan to spend the night at this place in between or are you looking for a place to just spend the day and plan on being in Tokyo by the evening?

I agree with Bamse's suggestions but if you have a rail pass, and maybe if you don't, you could consider Takayama as one possibility. I guess theoretically even Shirakawago may be possible to squeeze in if you plan correctly.

Takayama
http://www.japan-guide.com/e/e5900.html

As you seem to have dropped Himeji you could consider replacing your trip there with Hikone Castle which is an easy half-day trip from Osaka/Kyoto
http://www.japan-guide.com/e/e7001.html

If you really like castles then Matsumoto Castle may also be a good option of a place to see on the way to Tokyo.
http://www.japan-guide.com/e/e6050.html

Hi!
Thank you all for your suggestions.

I do not have a rail pass this time,since I will effectively be spending only 5 days in Japan.
I want one night somewhere between Osaka and Tokyo.
Since it may be cold, I was mostly thinking about cities,but I think Ise would be interesting too.
I am used to a cold climate (but I don't particularly enjoy it),so I will bring warm clothes.
I would like some days in Tokyo too before I leave. So I thought 2 days in Osaka and 2 days in Tokyo with 1 day to spare.

Takayama sounds interesting,but may be too demanding for my schedule.

I went to Hakone and Kamakura the last time I was in Japan.