It certainly looks like V. gloiocephala (=V. speciosa), and had you found it near the West Coast, US, I would have suggested that without hesitation. I was not aware, however, that this species could also be found in Japan.
The common name is “Paddy Straw”, but I figured that was a different species of Volvariella.

Here’s a link for what I think these should be: http://zakki.jp/ajiwai_kinoko/sirohukurotake.htm

Definitely Volvariella.

Alan, I appreciate your consideration.
Sorry I forgot to add this photo that shows the volva.
Pluteus don’t have Volva right? These don’t grow really attached to anything, but just in their own little volvic shell like an amanita.
I think this is probably the same as my recent Volvariella observation, sorry I don’t know how to add links.