What is Japanese high school baseball?

I am going to introduce Japanese high school baseball quickly.
 
Slide 1;
This graph shows the number of Japanese high school baseball players and schools joining the Japan high school federation.1-1)
Both numbers have been decreasing recently.
This tendency is especially strong in the case of players.
 
There are some reasons in my opinion. Firstly, a declining birth rate is causing fewer young people. Secondly, playing baseball costs a lot of money. Their parents cannot spend much money for their children playing baseball because real wages have substantially decreased during the last two decades in Japan. Lastly, other sports are getting popular.
 
Slide 2: 
There are 4 big tournaments in Japanese high school baseball. Especially Spring and Summer Koshien are the oldest traditional tournaments. The venue for the two tournaments is Koshien Stadium which was built in 1924. Koshien is a symbol of high school baseball. Many players have a dream of playing in Koshien. However, the number of schools that can take part in the Koshien is limited. Therefore, Koshien Stadium is extremely valuable among players.
 
Slide 3:
As I described, Japanese high school baseball is very historical. So, it has produced many dramatic teams, games, and achievements. The number of teams who dominated the spring and summer koshien in the same year is only eight over the long history of more than 100 years. Daisuke Matsuzaka who was called a monster of the Heisei era led Yokohama High school to a straight victory in the spring and summer tournaments as an ace pitcher. Matsuzaka played in NPB and MLB.
　 
The number of teams to win the 4 big titles in the same season is only one. It is Yokohama high school with Matsuzaka.

Now the season of the summer Koshien is approaching.
Osaka Toin high school is receiving a lot of attention because it has already won two titles such as the Meiji Jingu and spring koshien.
It is aiming at a three-time spring-summer winner in the same year and the second team to win the 4 big titles in the same season.
But, first of all, it must win the Osaka prefectural tournament known as a battleground.
(KAISPO No.1193)