We report a planning study to develop an integrated framework, on which a fusion power plant can be virtualized and simulated. As an effort to develop software for designing Korean DEMO (K-DEMO) fusion reactor, key technologies are identified with a structure to organize and integrate them. Strategies and directions for the development are proposed considering the Korean national plan to invest on the 4th industrial revolution technologies such as digital twin, artificial intelligence etc. Also, a road map for the development is proposed, in which 4 development phases are established in close connection to the Korean fusion energy R&D plan. Starting with the development of Virtual KSTAR (V-KSTAR) in the first phase, the roadmap proposes to develop Virtual DEMO (V-DEMO) in the final phase. The deliverables from each development phase are defined with discussions on their applications to the K-DEMO design activities.