Just to put it in perspective. Japan is one of those "no tipping" cultures, though there are exceptions. They pay the staff and it is note expected to leave a tip at restaurants or hotels etc. Again there are some exceptions and ways of doing so for outstanding service or things like after midnight taxi rides where you can but I won't go into the details of when it might be appropriate or how it is done as its not germane. In general, Japan is no tipping.
The reason I bring this up is that some hotels and restaurants and stuff have a sign in the room, menu, etc that says, in English, something like the following. They probably don't even say this in Japanese -- its for the tourists who come from tipping cultures.
(I'm making these words up but I have seen this in many hotels etc_
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No Tipping. In Japan, tipping is not expected or required. The staff are adequately paid to do their job. A 10% service charge is included in the price of the service, which is shared amongst all staff. Mp tipping is expect or required
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That sort of thing. It's not a service charge listed separately. It's in the price already that they quote you when you book the room or the food. They just explain it so the dense Americans understand how it works.