Just got back from Japan and am already planning a follow up trip

I went there in November and thought it was really cool but was too busy to do much. I've been listening to a lot of Japanese music and am now planning on going for the full month of February. I've never been anywhere for a month before and have no idea what to bring. How much luggage should I have? How much living out of a bag sucks? I'm gonna be sharing a room at a guesthouse for the first week so where should I keep my luggage?<br><br>The only trips I've ever taken have been a week or less. Any general advice for a month long trip?<br><br>edit: for those who asked why I'm planning on staying in one place for a month: I'm not. I'm gonna be in a different city each week. so a week in Tokyo, a week in Sapporo, a week in Osaka, a week in fukuoka, etc.