Also, why is dirt from the Koshien stadium so treasured? Makoto Kosaka explains in The Japan Times, “The dark side of the Koshien dream“:
How to explain Koshien’s massive popularity? In short, these boys of summer represent the best qualities found in Japanese sports: a self-disciplined work ethic, teamwork, resilience — qualities valued not only in sports but in life. Players who carry home Koshien’s sacred dirt, a memento for any athlete who makes it to the field, are valued in Japan by future employers and idealized by viewers.