Little is known of Sano Castle . It is mostly connected to its nearby castle, Karasawa Castle, both of which were next to Sano, the corresponding castle town for the two castles during the Edo period. The Sano Clan had previously built Karasawayama Castle, which had been established since the 1400s. In 1602, there was a great fire in Edo castle, which could be seen from Karasawayama Castle. The Sano clan sent their condolences to the Emperor. Some historians say that when the Emperor realised that Karasawayama Castle looked down on Edo, he told the Sano clan that there was a law against this. In the same year of the fire, 1602, the Sano clan, rebuilt another new castle at a lower point on the hill - this castle was named Sano Castle.