On the right is the Tsume-mon, a large, black gate just before one enters the honmaru area. It was a natural funneling point for any would be attackers.
Kochi Castle, in the former Tosa domain, was originally constructed in 1601 following Tokugawa triumph at the Battle of Sekigahara. Most of the structures you will see here date back to the early-mid 1700's making it one of only twelve original castles left in Japan. It is definitely worth a visit for any castle lover, although it's quite a journey from Osaka (around five hours, all-together).
<i><b>Kochi Castle. Kochi City, Kochi.</b></i>