Takahashi (2004) advocates the Japanese-style seniority-based system, particularly the idea of “new work in reward for work,” which is termed as the Work–Work Theory. This paper highlights the characteristics of the Work–Work Theory system in comparison with the idea of “pay in reward for work,” which is termed as the Work–Pay Theory. According to the Work–Work Theory system (i) differentiation of work accelerates differences in promotions and pay; (ii) as workers are dissatisfied with their current work situations, they may want to change their work situations by coming up with new and better ways of doing things, that is, challenging the status quo; (iii) supervisors select the right personnel for a job; (iv) implement regular changes in personnel to reward workers with their new work; (v) working together enables the company to grow; and (vi) under the Work–Work Theory, work assignments that gradually become more challenging provide intrinsic motivation, which becomes exciting (waku-waku in Japanese). If it is not exciting, it cannot be called intrinsic motivation. Thus, the Work–Work Theory drastically changes the motivational approaches derived from the self-determination theory to the honest practice of intrinsic motivation.