I'm currently contemplating extending my stay in Japan, but I'll have to budget everyday costs before I can choose a return date that will allow me to stay as much as I can without risking running out of money halfway through.
I already have the plane tickets and two weeks of AirBnB lodging paid, but after that I'll probably be relying on those sites that let you do volunteer work to get lodging, so that my friends and I can roam around rather than getting stuck in one place like I did last time.
As far as expenses go, I think everyday costs would be about ¥1,500 a day on average (which would account for two ¥500 meals and a couple train trips), but I don't have a clue of the costs of travelling out of Tokyo and into smaller towns, or going from there to Osaka/Kyoto while stopping by any towns in between that'd be worth our while. Shinkansen and more expensive trains lines are obviously out of the picture for the sake of keeping our budget as light as possible, and we'd love to do work-for-lodging in as many places as we can to keep that side of the budget on the lower side as well.
Summing up my thoughts, I'm trying to research towns that would be worth visiting, and some help to make sure I don't underbudget for our travels and end up staying for longer than my wallet can hold out. I'd obviously love it if I could just do freelance work through the Internet and wouldn't have to worry about running out of money, but having a clear worst-case budget would be best so that I can set my plane ticket's return date accordingly.