Beyblade: Shogun Steel (TV Series 2012–2013) - IMDb
If ya don't know, it is mentioned in the Manga that Kenta is in 5th grade at the beginning of Fusion. Maybe 11 years old. Besides Ryuga's body being over 100 years
Takanosuke x sakyo :shogun steel and kenta x ryuga beyblade metal fury | Beyblade characters, Anime characters, Disney cartoon characters