Yojiro Sengoku, general manager of the Kyoto Bloodshed Hotel, is a master of Reigen One-Sword Style. He taught it to the hotel staff. The house is a respite under a veil, then a classroom where Chihiro copies Iai off Kuguri, then a demolition when Hiruhiko spends Play. Toto takes Sengoku’s head as a blood sample to confirm who is in the building.
Why a hotel has a style
Reigen is not Iai and not Sand-Bone. It is the reason the staff are not civilians in the useful sense. The hotel page is the building. This page is the syllabus the ten treat as furniture. See Kyoto Bloodshed Hotel, Sengoku, Toto.