The story
From Japanese 和室 (washitsu わしつ), from Middle Chinese 和 (ɣwa, a gloss for ʔwa 倭 "Japan") + 室 (ʃit "room").
Etymology from Wiktionary, CC BY-SA 4.0.
washitsu
Today it means: A Japanese room with tatami flooring and usually sliding doors. Full definition →