Dozens of grown men from their 30s to 60s crowd around the tatami mat room in Kagetsuen, a Shizuoka Prefecture ryokan inn, and begin playing with their train sets. More than 90 percent of the inn's guests are adults who enjoy playing with toy trains. These mature train setters have not only kept the inn afloat as others around it have fallen into oblivion, they've helped it grow in a prime example of the otaku business that's now booming throughout Japan, according to AERA (7/18). "Thanks to trimming down our target market, we could stay in business," Eiji Misu, Kagetsuen's...