A concept on a ring-like semisubmersible for ocean space utilization of middle water area was proposed in the 1st paper. Principal concept of this structure may by summarized by the following items ; semisubmersible, ring-like shape in plan, supporting structures and connection system. The structure is anchored by supporting structures at several points and a special connection system between a semisubmersible and supporting structures is adopted, which enables such a function that the structure is almost rigidly connected with supporting structures in case of severe storm but almost loosely connected in case of severe earthquake. In this paper subsequent to the previous paper, firstly, some new environmental conditions are collected on a site, the Ise Bay. Secondly, characteristics required for connection system are investigated by simulation and determined. Thirdly, stability of supporting structure is discussed based on several design guidances. Finally, optimization on the number of supporting structures is carried out in accordance with a flow chart developed by some previous studies and it is proved that the number is reduced to a half of initial number.