The "mizunote", which has a dimension of about 120 metres (394 ft) from east to west and 160 metres (525 ft) from north to south, was situated to the east of the "hon-maru". The "mizunote" is a "kuruwa" which has a well or a reservoir for drinking water. In Fukuoka Castle, the "mizunote" was built with a catchment reservoir which, in times of siege, also played the role of a sutebori-moat which forced the enemies to take a roundabout way to attack. In addition to the sutebori-moat, there was an L-shaped "obi-guruwa" along the sides of the "hon-maru" and Ni-no-maru, enabling simultaneous defensive fire from various levels. According to a report ("The Intelligence Report on the Provinces of Chikuzen, Chikugo, Hizen and Higo") on this castle which was made by a shōgun's "shinobi" or ninja-spy, there was a flower garden surrounded by bamboo bushes to the south of the reservoir.