Japan doesn’t have to be terribly expensive to travel in. There are many options for cheap eating and lodging. Just about every convenience store has a good selection of decent food and they are everywhere. Street food and cafes are not as expensive as a restaurant and are often run by families that are famous for what they do. Airbnb, guest houses and my new favorite, coffin hotels are way cheaper than hotels and ryokans. Do try and save up to stay at a ryokan especially, in the wakayama district. It is a great experience, they have amazing food and public baths. Some of them are heated by hot springs. Before entering japan sign up for a JR pass for train travel, it will save you a lot of money on trains. There are cards for buses, local trains and convenience stores In Tokyo that work like debit cards that you can keep recharging with money. I think they get a discount when using them and it really simplifies the process instead of carrying around tons of money. The brand we used was called Suica but there were others. I also, would recommend some web searching but websites like japancheapo.com and youtube have tons of tips for great ,cheap things to see and do.