MATSUE -- One of the earliest known pictorial maps of Edo Castle, which was expanded by Shogun Tokugawa Ieyasu, has been found here according to an announcement by the Matsue Municipal Government in Shimane Prefecture on Feb. 8.

The 27.6-centimeter by 40-centimeter map, which is known as "Hajimezu," or "the map of the beginning," confirms that the structural design of the tower keep at Edo Castle around the start of the Edo period was similar to that of Himeji Castle in Hyogo Prefecture. In addition, the map shows that the entrance and exit on the south side of the castle keep -- which were designed to deter enemy invaders -- were very similar to those found in Kumamoto Castle.

Commenting on the pictorial map, a specialist stated, "The map is evidence that Ieyasu had a major battle in mind as it shows the castle right before the Siege of Osaka. Ieyasu built what could be the strongest castle of the time."

According to the Matsue Municipal Government, the oldest known pictorial map of Edo Castle is the "Keicho Edo" map, which measures 80.6 centimeters by 81.7 centimeters, and is kept in the Tokyo Metropolitan Central Library. It is thought that recently discovered Hajimezu was drawn around the same time as the Keicho Edo map, between 1607 and 1609 (or years 12 to 14 of the Keicho era), judging by clues such as the name of the feudal lord on the picture.

It is common knowledge that the tower keep at Edo Castle was rebuilt by the second Tokugawa shogun, Tokugawa Hidetada, and the third shogun, Tokugawa Iemitsu, but the architectural details of the castle during the early Edo period under Ieyasu's rule are unknown -- as the castle was burned to the ground following the "Great Fire of Meireki" in 1657.

In the Keicho Edo map, the towers are shown to be apart from one another, but in this recently found Hajimezu map, they appear to be connected, judging by the black-colored illustrations. To the north and west sides of the "large keep tower" are "small towers," and it can be seen that they are connected with turrets and walls.

Furthermore, the map shows a winding stone wall passageway that enabled castle-dwellers to attack any invaders with bows, arrows, and guns from any angle to the south of the castle keep. It can be said that the defense-related aspects of Edo Castle at this time resemble those of Kumamoto Castle -- which was built by the feudal warlord Kato Kiyomasa, who was renowned as a famous castle builder.

The Hajimezu map was one of 74 pictorial maps that made up a set of "top secret" maps which were donated to the Matsue Municipal Government in 1953 by a male citizen. The Hajimezu was found following an extensive investigation, which was conducted after an old pictorial map of Osaka Castle was discovered in July 2016.

The person in charge of the investigation, professor Yoshihiro Senda of Nara University, says, "There are very few historical documents relating to Edo Castle that date back to the era of Ieyasu. As the Matsue domain was a "shinpan domain" (ruled by feudal lords related to the three main branches of the Tokugawa family), it was probably possible to keep the pictorial map in good condition, despite there being strict rules and regulations."