## 2 Prior Research and the Positioning of This Study  
Basic income (BI) is a social policy that has received widespread public attention in recent years as an alternative to various social welfare programs. BI has been hailed as a kind of ideal social policy because it reduces the operational costs of social welfare, which entail enormous expenses [14], and frees people from forced subordination to poverty-based labor [15; 1]. There also exist older ideas similar to BI, such as the proposals by AgrarianJustice [16] and others. In the 1970s, a negative income tax was first suggested [17], and many demonstration experiments were conducted in the United States [7; 8]. A negative income tax has social implications and ethics and norms which are different to those of BI [18]. However, these empirical experiments have similar characteristics, and their results are also used in the considerations related to BI [7]. [PERSON] [8] synthesized the analytical studies of these empirical experiments, including the impact on health [14; 19; 20], the labor market [7; 15; 21; 22], the educational effects, and family relationships. Rather than negative income taxes, BI experiments have been conducted in Finland [3] and California [4] in recent years in response to the growing BI debate, and the results have been subjected to analysis [23]. Based on these results, some have argued that it is already satisfactory as a proof of concept [24]. Some people question the system's effectiveness [25], and some believe unemployment insurance is more beneficial than BI [26]. In addition to the aforementioned labor supply issues, there is the financial side; [PERSON] states that implementing BI in the U.S. would require an amount equivalent to about 75% of total federal government spending in 2017 [25]. However, the issue that has drawn the most attention from BI's opponents is labor supply. Several counterarguments have been presented that argue that although a slight reduction in work motivation may be observed, it is not a major issue. This is evidenced by experiments such as the negative income tax demonstration mentioned earlier [7; 15; 23; 27; 28; 29]. However, some have argued that the demonstrations are problematic because of the way the experiments are set up and because of the changes in the implementation planning phase [5; 6]. Moreover, a Hawthorne effect-like phenomenon may have occurred during the demonstrations [7]. If BI were implemented uniformly for all citizens, the response would be different. Furthermore, since the demonstrations used time-limited BI, it is conceivable that the behavior of the participants may be different from that in a situation in which permanent payments were guaranteed (e.g., behavior that views the period of payments as a period of preparation until after the payments are completed) [9; 21]. Even in the positive camp's theoretical framework, a temporary decrease in the labor force is still assumed [25], and empirical experiments have observed a 5-13% decrease in the labor supply [8; 21; 30]. Although these studies have focused on households' willingness to work, a similar analysis of the impact of BI on the labor market from a corporate perspective also found an 11% decrease in labor supply [31], suggesting that a labor force decrease of around 10% would likely occur. As such, the analysis of BI and its relationship to the labor supply is still unclear. [PERSON]'s work on the issue of BI presents an important and thought-provoking perspective on this labor supply issue. According to [PERSON], \"The more of his friends who attend, the more likely he will attend\" [32]. This perspective also includes the consideration of the possibility that work motivation may change depending on comparisons with the incomes of others. Although [PERSON] has considered the potential impact of relative income equality on changes in work motivation [33], we are unaware of instances of such changes being modeled in the impact analyses of BI.