Three floor plans adopted in 1951 were called 51A, 51B and 51C after the year. The 51C plan had a floor area of only about 35 square meters. It came to be regarded as an excellent and highly functional plan, and later apartment layouts took it as their prototype.
The designer Suzuki found that a larger kitchen could also serve as the place to eat. The bedrooms could then be divided, while eating and sleeping still happened in separate rooms. This is said to be the origin of the Japanese dining kitchen, the DK.