Success in software development is not simply “a person” or “a team” succeeding in development, but rather the execution of a smooth “shift to the next-generation” of developers, who continuously upgrade a single software product over a long span of time. In this case, different generations of developers share the source code. This paper analyzes this process using “Denshin 8 go,” Japanese free software as one example. Initially, the original creator, Ishioka developed Denshin 8 go single-handed as closed source software and succeeded in motivating users through frequent upgrades. Several years after the initial release of Denshin 8 go Ishioka lagged behind in much needed upgrades, but one user group continued to use Denshin 8 go and was eager to improve the software. He disclosed the source code to the group, which in turn carried forward the process of development. As this case shows, the viewpoint that alternate generation of developers outside of a single company is caused by success in software development is known as “open source” software development. However, the reverse is not necessarily true. That is, simply becoming open source does not guarantee successful development.