Carrying a backpack will make your back stronger, you don't "save" it by using a wheeled suitcase unless you already have a health condition. Ideally the backpack will have a strap to go along your chest for stability.
Pretty much every hotel in Japan has a laundry machine, although I don't know of any suites that include one, unless you're going for a managed apartment.
Pretty much every hotel in Japan has a laundry machine, although I don't know of any suites that include one, unless you're going for a managed apartment.