Max Matsuura held a songwriting camp in March to make Ayu songs (March 2020)

[truehappiness]

It's probably Max's house in Hawaii and he lets her use it when they go there. He moved over there quite some time ago iirc. Given how close they are, I think Ayu probably just has keys to the place. Back when we saw her on a scooter or something a few years back it must have been the driveway to this mansion.