Manga is also a form of promotion.
Especially if the works of Mashiro Takumi and Takagi Shuutoku became widespread across Neon and gained international traction, once the main character's name became well-known, his neighborhood, and the shop he vowed to protect, naturally gained fame as well.
Take for example Makoto Shinkai's recent work, "Your Name." Although it is an anime, not a manga, the promotional intent is the same. Fans should be familiar with the concept of a "pilgrimage to holy sites." As "Your Name" became a hit both domestically and internationally, the real places featured in it immediately became popular tourist destinations.
Bringing it closer to home, there's "Your Name," but look further back, and there are works like "Slam Dunk" that have undeniably made places like Kanagawa Prefecture, Xiangbei High School, Kamakura, and so on, increasingly known to the public.
Xia Yu was looking to make an investment.