The present paper describes the advanced features and powerful flexibility of the three-dimensional computer program developed by the authors aiming at hydroelastic response analysis of various types of Very Large Floating Structures (VLFSs) in waves in water area of complicated environment close to real situation. In order to illustrate its power, two preliminary tests have been conducted additionally. An asymmetrical VLFS with abrupt change of its rigidity and weight has been examined and hopeful results have been obtained with the help of a 'semi-wet' modal formulation proposed in the previous report. Then the treatment of variable water depth has been tested. The corresponding hydroelastic responses of a VLFS over sea-bottom topography have been compared well with those by Utsunomiya, thus its geometrical flexibility has been proved again. Final challenge is for the real MEGA-FLOAT models. Simulation for the 1000m MEGA-FLOAT Phase-II model has been conducted, taking the real breakwater into consideration, and then reasonable dynamic behavior has been obtained. Another test is for the 'Tokyo Bay airport' model, 4770m long and 2055m wide at the widest. Simulated results have shown the typical hydroelastic behavior of VLFSs and agreed comparatively well with those for the similar very large rectangular plate, thus normal computation has been confirmed. Thus, the applicability of the present computer program has been again proved to a variety of real VLFSs. Conclusions are that the present 3D hydroelastic response program is a powerful working tool for practical VLFS investigations for the detailed design.