Maybe, but 210,000 yen is roughly $1,400 dollars. That is probably a month's rent for Kobayashi.
For the relevant comparison, you should do the computation in terms of
purchasing-power parity, rather than in terms of
exchange rates. And that means that ¥210,000 is more like US$2,135 — about 50%
more than you calculated.
But we are talking about something that Kanna would have still treasured millennia after the death of Kobayashi.