He started out playing for the FC Tokyo youth system, specifically the U-15 Shenzhen team. His team won the 2003 Japanese Club Youth U-15 Championship. He later attended and played for Maebashi Scholarship High School. With his help, the team made the semifinals of the 2008 All Japan High School Soccer Tournament. He scored 2 goals in 5 games and was named to the Tournament All-Star team. He also represented Japan in various U18 tournaments at this time, including the 2010 AFC U-19 Championship qualification. After graduating from high school, he refused J.League Division 1 offers in order to play for Chuo University.
Musaka captained Japan during the 2010 AFC U-19 Championship in China, scoring a goal and leading his team to the quarterfinals of the tournament, where they lost by a score of 3–2 to South Korea. He played in various other international youth tournaments, such as the Dallas Cup, the SBS Cup, the Sendai Cup and the Milk Cup.
In 2011, he was chosen to represent his country at the 2011 Summer Universiade. He scored two goals in the tournament and had an assist in the championship game, where Japan beat Britain 2–0 to win its 5th Universiade soccer title.[2]
