As a freshman, James averaged 21 points and 6 rebounds per game for the St. Vincent-St. Mary varsity basketball team. The Fighting Irish went 27–0 en route to the Division III state title, making them the only boys high school team in Ohio to finish the season undefeated. As a sophomore, James averaged 25. 2 points and 7. 2 rebounds with 5. 8 assists and 3. 8 steals per game. For some home games during the season, St. Vincent-St. Mary played at the University of Akron's 5,492-seat Rhodes Arena to satisfy ticket demand from alumni, fans, and college and NBA scouts who wanted to see James play. The Fighting Irish finished the season 26–1 and repeated as state champions. For his outstanding play, James was named Ohio Mr. Basketball and selected to the USA Today All-USA First Team, becoming the first sophomore to do either.