The purpose of this study was to clarify the causal relationship between the “flow of a game” in basketball, defined as “the situation in which 4 periods, which consist of a division time of 10 minutes, advance gradually while having an influence on each other”, and its outcome, focusing on the interrelationships of the 4 periods. For this purpose, a hypothesis was established that the “flow of a game,” in which “factors causing changes in conditions” cannot be overlooked, consists of 4 periods, each creating opportunities that finally affect the outcome. In order to test this hypothesis, an analysis was performed of 1044 periods in 261 games in Japan’s strongest university league, the Kanto Men’s First Division League, based on the following 3 perspectives: (1) the importance of each period; (2) the mutual dependency among the periods; and (3) the relationship between the difference in cumulative scoring and outcome. The results were subjected to logistic regression analysis and covariance structure analysis, and the following 3 points were clarified: (1) Periods that influenced the outcome were the first, third and fourth, ranked in importance as third > first > fourth > second. (2) With regard to mutual dependency among the periods, the points difference in the preceding period in the sequence “first → second (cumulative),” “second (cumulative) → third (cumulative), “third (cumulative) →“fourth” created an opportunity in the following period. (3) A cumulative score difference of less than 8 points by the end of the third period was associated with a high potential for coming back to win. These findings should be applicable to coaching in various games under the official rules of the FIBA as new practical guidelines for closely analyzing the causal relationships between the unique “flow of a game” and outcomes in basketball that take place over 4 periods.