The titular Hanagata is a Junior High student who used to be an ace Little League Pitcher until he busted his shoulder. Now, in Junior High, he has decided to focus on his batting. But, the School has been banned from official games, and the baseball club has reluctant members.

From Wikipedia
In the manga and anime, Tiger Mask (whose real name was Naoto Date) was a feared heel wrestler in America who was extremely vicious in the ring. However, he became a face after returning to Japan when a young boy said that he wanted to be a villain like Tiger Mask when he grew up. The boy resided in an orphanage, the same one that Tiger Mask grew up in during his childhood. Feeling that he did not want the boy to idolize a villain, Tiger was inspired to be a heroic wrestler.

The main antagonists in the manga and anime was Tiger's Cave, a mysterious organization that trained young people to be villainous heel wrestlers on the condition that they gave half of their earnings to the organization. Tiger Mask was once a member of Tiger's Cave but no longer wanted anything to do with them, instead donating his money to the orphanage. This infuriated the leader of the organization and he sent numerous assassins, including other professional wrestlers, to punish him.

Most of the environment and characters were fictitious, but real-life pro wrestlers Antonio Inoki and Giant Baba were included in the manga and anime as well.

From Dragon and Tigers Manga: Joe Yabuki is a young man living in the slums of Tokyo. But, one day he meets Danpei Tange, a former boxer, who discovers his potential in boxing and tries to make him into a champion. Due to petty crimes, Joe is sent to a juvenile prison. There Joe mets Toru Rikiishi, a promising boxer, who knocked him out with one blow when he attempted to escape prison. Slowly but surely, Joe realizes his own potential. Joe begins his boxing life, step by step, with only one goal in mind... To Defeat Toru Rikiishi !! NOTE: Chapters 1-10 are read left to right, the remaining chapters are read right to left.