Keiunkan is a state guest house that was built by a wealthy merchant in Nagahama for visits from the Emperor Meiji during the Meiji period (1868-1912). It is currently open to the public as a sightseeing facility. In early spring they hold the "Nagahama Plum Tree Bonsai Exhibition," which brings in many tourists. They also have impressive gardens that overawe all who see them.
2-5 Minato-cho, Nagahama City, Shiga
9:30～17:00 See the homepage for details of opening days.