I do not know, but the tub is hinoki wood and made by Sea Otter Woodworks: http://www.custommade.com/by/seaotter/

Zen Bathworks is the brand name for SeaOtter Woodworks. Same amazing craftsmen, same focus on building beautiful and reliable ofuros. The finish is oil, wax, and elbow grease! Visit us at zenbathworks.com