Carrying a backpack in Japan is perfectly acceptable and very common for tourists, but you should be mindful of local etiquette. In Japan’s crowded cities, a backpack can be seen as an obstacle; the standard social norm is to wear your backpack on your front or hold it in your hands when boarding a crowded subway or train to avoid accidentally hitting other passengers. Many shops with narrow aisles also appreciate it if you carry your bag in front of you. While Japan is incredibly safe with very low rates of theft, many travelers prefer the "backpack on front" look in busy areas like Shibuya as an extra precaution. From a logistical standpoint, Japan is very "suitcase-friendly" because of its smooth pavements and ubiquitous elevators, but a small backpack is ideal for day trips. If you have a large "backpacker" style bag, it is best to use a luggage delivery service (Takkyubin) to send it to your next hotel rather than lugging it onto a busy Shinkansen.