He graduated from Japan College for Physical Culture in 1940.
At the 1952 Summer Olympics he won the silver medal in the vault with a score of 19.150, which was 0.050 short of the gold medal. Two years later he became world champion in the floor exercise, sharing the first placed with Valentin Muratov. He also won a silver medal with the Japanese team and a bronze at the parallel bars.
At the 1956 Summer Olympics Takemoto won three bronze medals: in the horizontal bar, parallel bars and rings; he also received a silver medal as part of the Japanese team. His main skills were on the floor exercise and he proved it once again at the 1958 World Artistic Gymnastics Championships, where he successfully defended his title. He also won silver medals in the vault and team event, as well as a bronze medal in the horizontal bar.
At the 1960 Summer Olympics Takemoto won a team gold medal and placed second in the horizontal bar.
Physical Characteristics: Height 160 cm (5 ft 3 in), weight 56 kg (123 lb).