Tohoku History Museum
If museums are not your thing then you are probably not even reading this article. If they to tickle your fancy, then Japan is a great place to visit as the Japanese government has a habit of placing large, well funded and modern museums out in the middle of nowhere. This means you basically get the place to yourself if you are willing to make the trek.
The Tohoku History Museum is a 25 minute train ride from Sendai station and a short walk out of the south exit. Do check the holiday calendar for days when the museum is closed (red 休館 means closed). Entrance fee is only ¥460 and free for under 18s (proof may be required for high school students).
You can read about the museum by downloading English language documents here. The main website is not maintained in English, however they do have free audio guides that are very recommended.

