Rival's Flag

(from ebookjapan):

A hot-blooded baseball manga by one of the biggest names in manga, Jiro Tsunoda!　Saburo is a boy who is passionate about baseball.

When he goes to his usual field for team practice, he finds an unfamiliar youth baseball team practicing hard and looking like pros.

They call themselves the "Meguro Idols" and display the team's "flag" on the field, and insist on taking it over!

After an argument, the team that wins the baseball game gets to use the field!

What will the outcome of the game be...?