洋館を増改築して使っているイメージです。
最近作った設定なので過去作と矛盾があっても許してください。
2F建て（＋屋根裏部屋）です。

It's got the image of an expanded and remodelled western-style house.
As this is a thing that I only recently made, please forgive any contradictions with any previous works.

It's a two-storey (+attic) building.