Yamamoto Takeshi was born in Japan and is 177cm tall, weighing 63kg. He is a Taurus with O blood type. His Future dream is to become a professional baseball player, and is a regular at the Namimori batting field. His favorite food is sushi, and his favorite drink is milk. His favorite instrument is the taiko (a Japanese drum).
Addressed as "Yamamoto" by almost everyone in the series, this baseballer-turned-Mafioso has a warm and friendly personality and is rarely seen not smiling. He is, however, very naïve to the point of believing that Reborn's Weapons are advanced kid's toys and that the mafia business is one big cops-and-robbers game.
Yamamoto's portrayal in the story is that of a stereotypical Japanese teenager; his name "Takeshi" and surname "Yamamoto" are both common Japanese names, his looks are quite ordinary for a Japanese teenager, he is a big fan of baseball (a popular sport in Japan), his family owns a sushi store, and later in the story, he uses a katana (a Japanese sword).
Future Yamamoto has shown to have learned everything about the Mafia and seems to be okay with it.