Kagami was in America until second year of middle school and has recently come back to Japan in his first year on senior high. He is determined to surpass "The Generation of Miracles" and become the number 1. Along with Kuroko, they're the only two freshmen allowed to play in matches. At the start of this manga, Kagami is shown to have a huge potential—good build, height, skill in basketball—but his strongest weapon is his inhuman jump. With those jumps (that gradually gets higher and higher every time he jumps), he managed to block his opponent's attacks.
He's really bad at studying and always get low grades even in English (even though he's a returnee!). He's unexpectedly good at cooking, since he lives alone, and he also has an enormous appetite, which is shown when he orders tons of burgers. In the past, he was attacked by a dog, and that made him afraid of dogs until now (but later on he's able to deal with Tetsu No. 2, Seirin's pet dog).
Even though it looks like they always disagree over things, he and Kuroko are actually on good terms, and they're called Seirin's Freshmen Duo.