Sekka Zusetsu (Picture book of sketching snow crystals called Sekka)
Illustrated books featuring patterns of snow compiled by Doi Toshitsura, the feudal lord of the Koga feudal clan, about observations of snow crystals. Toshitsura named snow crystals “Sekka (snow flowers)”, and 86 kinds of snow crystals were illustrated in Sekka Zusetsu, and 97 kinds in Sekka Zusetsu – Continued. Both volumes were published as private editions with the use of woodblock printing. It is said that Takami Senseki, a senior retainer of the Koga clan, played an important role in the publication of the book. Toshitsura worked hard at the observation and study of snow crystals for approximately 20 years with the use of microscope. Toshitsura is known by the nickname of “the feudal lord of snow”. The Sekka Zusetsu is in the possession of this museum and has an oval shaped stamp of “Katsu Yasuyoshi”, and therefore it is thought that the book might have been possessed by Katsu Kaishu.