The main building of Nezu Museum (根津美術館), the art museum in Minato district, Tokyo (東京都港区). It houses the private collection of Nezu Kaichirō (根津 嘉一郎) on pre-modern Japanese and East Asian art. Thanks Jobbo.
Two different 84 Yen stamps were used. They were cancelled at Tokyo Hokuso on 7.12.2024. Maybe cancelled by night shift, as 18-24 in the postmark indicating time.