The King of Baseball .

Yamamoto is a superstar baseball player at Namimori Junior High School and prior to joining Tsuna's family baseball was the biggest part of Yamamoto's life. Yamamoto's really good at it too, he made it to be a starter while he was still a freshman and is considered to be trusted by everyone and followed by fangirls.

Yamamoto drives himself very hard because he considers baseball to be his life. He becomes depressed and concerned when his averages start to drop and his fielding is going down. When Tsuna meets him Yamamoto says it may be the first time he doesn't start since he began to play. When Yamamoto breaks his arm after training to get his edge back he's ready to commit suicide because he believes he has nothing left.

"After the Baseball God threw me away, I've got nothing left." Ch. 05 Pg. 10.

Tsuna is the one who takes Yamamoto out of it and makes him realize that he can't end his life over something so small and ends up following Tsuna from then on. Throughout the series he continues to play baseball but not as often. Reborn even gives him a baseball bat that transforms into a sword.

In the Ten Years Later Arc Yamamoto still practices his baseball and wants to give up his sword to play again but refuses to completely abandon Tsuna. Squalo doesn't want to lose a rival and constantly sends Yamamoto tapes of Squalo's "Road to be the Sword Emperor" in order to keep up his "fighting spirit". Needless to say baseball & the mafia, both are serious business.