Why are the nation-wide highschool students' baseball games so interesting for many Japanese? Of course they are very different from professional baseball. The system is a tournament, and so they should fight with all their force.
Each team is selected from each prefecture, and so people of each prefecture will cheer their local team. It's a kind of battle among Japanese prefectures. It's exciting for many Japanese.
And the highschool students' baseball games are not related with money. I think that it's one of interesting factors, because originally sports are the amateurism.