This study first outlines the classic Marshallian and Weberian theories of industrial agglomeration, highlighting the difference between Weber's theory, which "discusses the process of agglomeration emergence, based on predictable profit, from a state of nothingness," and Marshall's theory, which "discusses the process of continued self-reinforcement of existing agglomeration." Consequently, one cannot expect to understand the dynamism of industrial agglomeration by viewing these two theories separately. This study integrates the two theories to identify a framework for viewing industrial agglomeration dynamically. Specifically, this paper pays particular attention to "gatekeeper"-type companies, which capture the demand from markets outside the industrial agglomeration and make use of networks within the industrial agglomeration to meet that demand.

This paper proposes to combine supplier-side and purchaser-side logic in a new model of Japanese industrial districts. We interviewed large retail firms that were purchasers for industrial districts and 21 small-scale firms located in Tokyo's Ota Ward and Joto area that were the suppliers. Our interviews clearly highlighted the importance of business practices called "Kouza" and "Chouai." Large enterprises on the purchaser side deal only with kouza-holding firms (direct suppliers) and chouai-saki, which coordinate sub-suppliers. The assumption of such business practices implies that firms holding kouza within the industrial district are a necessity for purchasers to enjoy economies of agglomeration.

The number of people who play video games has become close to three billion during the COVID-19 pandemic. Yet, video games' causal effect on well-being has been understudied, and most studies have relied on correlation. We select k6 and SWLS for measuring well-being and apply causal inference methods. We take advantage of a natural experiment where lotteries for purchasing video game consoles---the Nintendo Switch and the PlayStation 5---created a random variation in access to video games. Using online surveys with 100,000 responses from Japanese aged 10-69 during the COVID-19 pandemic, we find that video game play impacts users' well-being positively. Winning a game console lottery positively affects well-being by 0.2 SD for the Nintendo Switch and 0.1-0.2 SD for the PlayStation 5. The instrumental variable approach indicates that owning a new game console has a positive impact on well-being by 0.6 SD for the Nintendo Switch and 0.1-0.2 SD for the PlayStation 5. In addition, a machine learning method reveals a striking difference between the heterogeneous effects of the two video game consoles. While the PlayStation 5 effect is smaller for teenagers, married, non-gamers, and females, such heterogeneity is not found for the Nintendo Switch effect.

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