All the Post Offices have ATMs, including one that is five (5) minutes from the ASLO conference venues.
The ATMs have longer operating hours than the Post Offices themselves, and they take most cards: VISA, VISAELECTRON, PLUS, MasterCard, Maestro, Cirrus, American Express, Diners Club, JCB, China Unionpay and DISCOVER.
You can convert the screen to English by pushing a button. Generally you push a button for the denomination (1000 or 10000) then the number of bills you want of that denomination.
For an order of magnitude estimate, 20000 yen in US dollars is equal to about $250.) If you wanted this amount from the ATM, you would touch the 10000 button then 2. If you enter 20000, the machine may think you want 200 million yen (2.5 million US dollars). This might be a bit more than your daily card limit!
The 7Bank ATMs also work and have an English option when you put in your card. These ATMs are found in 7-Eleven convenience stores, which are open 24 hours a day. There are several of them in the Otsu area. As noted in our ASLO travel directions, there is a 7Bank ATM in the south terminal of Itami airport.
Credit cards are increasingly used (e.g. JR Rail offices), but not everywhere (not all restaurants, for example).