We went as a family of four in October. Flights were OK (Cathy Pacific, in their January sale) and accommodation was relatively expensive in Tokyo (definitely not £30 a night) but food/drink/transport/shopping were way cheaper. Easy to feed four of us in an izakaya for £40 including drinks. Shops like muji & Uniqlo half the price they are here. We ended up needing to buy an extra suitcase. Was an incredible trip