If you plan to use JPY cash upon arrival in Japan, we recommend that you exchange money in your home country or at the airport in advance. There are only a few banks in downtown Osaka that can convert dollars into yen.
In Japan, there are a limited number of banks that accept cash exchange. Small amounts can be exchanged at currency exchange machines located at major train stations.
Smart Exchange
https://smartexchange.jp/en/
World Currency Shop
https://www.tokyo-card.co.jp/wcs/en/