Get change (coins) and try things from vending machines - particularly, the hot milk tea on a cold morning, but be prepared to carry your trash all day until you get back home. Try foods in supermarkets or convenience stores, especially weird candy. Bring Google Translate to use live translation mode. If you're not sure if your phone has the right bands for high speed internet, or how to get a sim card, you can rent a phone, though a dude in a suit will come deliver it to you and make you sign the contract. Eat a giant bowl of curry rice at a curry rice place where you choose your order from a giant ticket dispensing machine. Make a friend and join them at an Izakaya. In Tokyo, definitely go to Golden Gai and do karaoke in a tiny bar. The Miyazaki Museum requires advanced tickets and is usually sold out. If you go to Hiroshima, do not miss the Peace Memorial Museum, Miyajima Island, the cherry blossoms, or the okonomiyaki.