You can exit and then take a shower. There’s a pay shower to the left of the exit from customs next to Tully’s coffee. An arriving JAL J boarding pass used to get you a free shower, not sure if it’s still the case. It doesn’t cost very much in any case.

Just exit normally take a shower and head into town.

alternatively there is a 24 hr sento inthe hotel villa Fontaine connected by walkway to the international terminal, more expensive but you get to have a bath as well.