Japan has a cash-friendly culture in transition. QR code payments like PayPay are everywhere for locals, but tourists generally cannot register (it requires a Japanese phone number and ID). Stick to IC cards and credit cards instead. Rural areas still prefer cash. Get a Suica card immediately upon arrival as it works on virtually all transit and at convenience stores nationwide.
Japan's most widely used QR code payment app, accepted at convenience stores, restaurants, taxis, and small shops across the country.