If anything, convert all indices to the same currency, such as the USD, and this must be done daily with the exchange rate in effect on that day, going back for all years. So now it shows a mix of exchange rates and stock prices. For local invest...
The best price I can find on Pentel Energel refills (e.g. XLRN5-C, XLRN4-C) is $1.45 each. Amazon Japan has a better selection, and 10-packs for ¥ 597 each. At the time of this posting, 100 yen is valued at ~$0.80 USD. So that’s $4.80 for a 10-pack vs. $1.45 each...