This paper presents the progress of the study on a pneumatic floating body following the previous paper presented at the WCFS 2023 Japan (Nakajima et al. 2023). It describes the theoretical background of an innovative design concept of the pneumatic floating structure that can be used for a Very Large Floating Structures (VLFS) like a floating city and/or floating airport located in the open sea. The pneumatic floating body has a unique feature of reducing rocking and tilting in rough waves caused by strong winds as it has an open bottom. The rigid connection unit such as 3D truss beams connect floating modules in which the open space can be used for housing lifeline. The pneumatic floating modules control their buoyant force by adding or reducing inner air pressure so that they can cope with variable loadings on the modules. Accordingly, any buildings having different weights can be built on a floating platform without the stress differences between the modules that are connected by 3D truss beams. This paper introduces so-called “Air Pocket Factor” that plays a key role in designing the pneumatic platform and proposes an image of architectural complex to visualize this structural system as an example.