Usually, do not tip in Japan.
At restaurants, taxis, hotels, and shops, simply pay the displayed amount. You do not need to leave cash or add a tip to the bill.
A service charge
Hotels and upscale restaurants may include a service charge. It is part of the bill, not an additional tip.
Otoshi or seating charge
An izakaya may add a small dish you did not order or a seating charge. This is a restaurant charge, not a tip.
Private guides
Only follow tipping guidance when it is clearly stated in advance by the guide or tour.