It looks like for 3000JPY I can buy into the Domestic Sakura: https://www.jal.co.jp/jp/en/dom/serv...nd/sakura.html

That works perfectly for us, $21 for a shower, food and drink, no brainer. I hacked through the web site in Japanese and was able to make a reservation, but it shows in my name not my wife's, fingers crossed that'll work. It says you have to pay in cash there. It also says you must have a reservation, you cannot do same-day walk-in and it is subject to being denied if congestion/crowd issues.

I'm not feeling super confident, especially since the reservation is in my name despite me logging in using my wife's first name (same record locator). Fingers crossed. I also read (on reddit) that JAL lounges only allow you in 3 hours ahead of the flight, but I spent 9 hours in the OWE First while waiting for a 9 hour connection to BKK just over a year ago, so not sure if that's accurate.