Except in Japan, the standard electrical voltage in all the countries we travel to is 220/240 volts AC, 50Hz. The Japanese standard is 110 volts. There is no need to bring your own adapter plugs or waste time trying to figure out if the power sockets would work with your battery charger. The hotels have proper set-up in each room to allow international guests to their devices without hassle.
Your personal electronic devices should be able to handle voltages between 110 and 240 for charging. If not, it would mean your devices are too old.