haven't seen japonica often in the US, but jasmine rice is similar and available pretty much everywhere.
in fact, jasmine rice smells and tastes better, and stickier!
in fact, jasmine rice smells and tastes better, and stickier!
Jasmine top, Japanese bottom
They have a completely different consistency when cooked and are used for different things.
it's has a similar stickiness, the taste is a bit different, but better imo.
it pairs well with asian dishes as opposed to american rices and can be used for sushi.
it's not 1:1, but it's certainly a good substitute when you can find japanese rice.
maybe it's how it turns out in the rice cooker.
either way, I've done it and it tastes good /shrug