The Ushiromiya Main Building on Rokkenjima is where Krauss Ushiromiya's immediate family resides. The building is where most of the murders take place in Umineko no Naku Koro ni. It features a fully-stocked kitchen, a parlor, and a large reception hall. Within the reception hall hangs a large portrait of Beatrice, with the witch's epitaph engraved beneath it.
- The exterior of the mansion is modeled after a Western-style mansion in the Kyu-Furukawa Gardens.