Kozan-kaku is a distinctive lodging facility designed by renowned architect Kazuyo Sejima and completed in 2000. Located in Mito's historic Sanonmaru district, this contemporary structure represents an important example of early 2000s Japanese architectural design. Sejima's minimalist approach creates an elegant spatial experience that seamlessly integrates modern hospitality with refined aesthetics. The building's thoughtful design demonstrates how contemporary architecture can respect its historic surroundings while establishing a unique architectural identity. Its completion marked a significant contribution to Mito's cultural and architectural landscape.