Background: Pachinko and pachislot are popular types of gambling activities in Japan. Prior studies in Japan have reported a concerning prevalence of gambling disorder among university students and adult players. While these studies have identified various gambling-related harms, Japanese research on harm-minimization strategies is scarce. Therefore, the present study aimed to analyze the effectiveness of low-investment pachinko and pachislot as a harm-reduction strategy. Methods: We also called gamblers who played for the normal amount as “normal-pachi players,” those who played pachinko and pachislot for half of the normal amount were called “half-pachi players,” and those who played for a quarter of the normal amount were called “quarter-pachi players.” To assess the effect of harm reduction, a one-way ANCOVA was conducted to compare the impact of the groups (normal-pachi players [n= 101], half-pachi players [n= 104], and quarter-pachi players [n= 100]) on dependent variables, namely the number of days players had gambled during the prior month, the total time and amount of money spent on gambling, debts caused by gambling, gambling severity, cognitive distortion, depressive symptoms, and disability. Results: We demonstrated that the amount of money spent by quarter-pachi players on gambling during the past month was lower than that of normal-pachi players. However, we did not find significant differences with respect to any other gambling-related harms among normal-, half-, and quarter-pachi players. Conclusion: Low-investment pachinko and pachislot can reduce the amount of money spent on gambling. It can thus partly act as a harm-minimization strategy. Moreover, the results of present study indicate that the level of disability at work affects various outcomes for gamblers. Given that 90% of the participants in this study were employed, the results of this study may have important implications for employed gamblers. Interventions should be devised to reduce work-related disabilities among employed adults with a gambling disorder.