Mitsubishi Temporary Headquarters (Building No. 22) (Taisho 7-1971) [Kotaro Sakurai and Taisho-era Architecture]

What did Sakurai's temporary Mitsubishi headquarters (hereafter referred to as the temporary headquarters, south side of the current Mitsubishi Building) inherit and develop from the American-style office building that Yasuoka attempted with Building 21?
The floor plan is a courtyard with a square-shaped common corridor, and the main entrance is planned in the center rather than on the intersection side, likely in consideration of access from Tokyo Station (1914), which has had an impact on the lifestyles of many people.
Next, looking at the plan, we can see that the number of rows of decorative bricks or bricks are illustrated. The concept of setting the floor heights of the temporary headquarters (steel-framed brick construction) and Building 21 (SRC construction) inherits the ideas of brick construction from the Meiji period.
Finally, we will introduce the elevation view from the Daimyo-koji side. Up until Building No. 21, the buildings had inherited the Queen Anne style with red brick, but the temporary headquarters is Secession-style with white decorative brick. The boxy facade, including the tower design, is a departure from Meiji-era designs, and can be said to be an exterior design that gives a sense of a new era.
By the way, why didn't they stick to the previous design?
Nobuyuki Ishihara recalls that he was ordered to redo the exterior, saying, "Make it a little more modern." But where are the blueprints for the Tudor-style exterior that Sakurai had completed? A search is currently underway.