IIRC, I've also read that they consider it helpful for allergy season. Japan supposedly has one of the worst allergy seasons in the world due to misguided industrial policy around timber.

TL,DR; After WWII Japan heavily incentivized reforestation to provide cheap domestic timber for industrial and defense purposes, but only with two types of trees, Japanese cedar and Japanese cypress. It turns out that even with this explicit industrial policy, it's cheaper to import timber, so trees weren't being cut down as fast as expected and the forestry industry had a declining workforce that couldn't maintain the forests. The resulting bi-cultural conifer forests grew so thickly that no sunlight reached the forest floor and these forests became devoid of biodiversity. And now all of these trees release a lot of pollen.

10 minute Youtube video explaining all this: https://www.youtube.com/watch?v=VC4gRGPbTqE