Been twice, once to Tokyo and second time to Osaka, Nara and Kyoto. Always felt at ease, comfortable and truly welcomed everywhere.
Just respect their way of life and especially their space.
An example of their kindness. We were travelling from Narita airport to central Tokyo on the Metro. Elderly gent saw me studying the map, asked where we were going to; he said there's a quicker route but involves a change of line. He then got off the metro with us, carried my Good Lady's suitcase, took us through a maze of platforms, put us on the correct metro, bowed and said goodbye. That set the tone for the holiday and it didn't disappoint.