This is an illustration of the plans for the façade of the castle keep in 1712 (Shōtoku 2) drawn with the aim of reconstructing the Edo castle keep after the Great Fire of Meireki.

A political reform called Peaceful Era of Shōtoku took place during the 6th Shogun Ienobu's period, and was led by the Confucian scholar Arai Hakuseki. It was Hakuseki who advanced the Edo castle reconstruction plan.
According to this illustration, the reconstruction plan of the castle towers, being based on the drawings of Kan'ei, proposed for an "orc spear" to be placed upon the top level of the five tiered five level castle wall and the building to be arranged with a Chinese gable and plover gable and the window back to be copper-clad.
Unfortunately these reconstruction plans never saw the light of day and since then the role of castle tower was fulfilled by the Fujimi Watchtower without the castle tower in the inner citadel of the Edo castle being reconstructed.