For foreign participants arriving at Narita airport, it takes about one hour to go through customs.
After passing through customs you will probably need to
exchange some money into yen.
There are exchange counters in the airport, and the exchange rate
there is reasonably good.
(The exchange rate as of July 1 was
yen.)
For the trip up to Sendai you will need to have about 20,000 yen.
However, you may wish to change a little more while at the
airport, as it is quite convenient there.
To help gauge how much to exchange,
please consider that an expensive (resp. inexpensive, typical)
dinner in Sendai might cost about 5,000 (resp. 1000, 2,000)
yen per person.
It is also possible to change money at the larger banks and the central post office in the Sendai city center. Cash and traveler's checks can be changed, but not personal checks.
It is not possible to change money on the campus of Tohoku University.