I te Oketopa 1964, i a Yokoyama he akonga i te Whare Wananga o Rikkyo, i tohua ia mo te roopu motu o Japan mo te 1964 Summer Olympics i Tokyo. I tenei whakataetae, i tiimata ia ka takaro i nga tukinga katoa mo Tsukasa Hosaka i whati i tona ringa i mua noa o nga Orimipia. Whai muri i tera, ka noho a Yokoyama hei kaitiaki whaainga i te kapa motu o Japan. I te tau 1968, i tohua ia mo Hapani mo te 1968 Summer Olympics i Mexico City. I tākaro ia i ngā tukinga katoa, ā, i riro i a Hapani te mētara parahi. I te tau 2018, i tohua tenei kapa ki te Whare Whutupaoro o Japan. I tākaro hoki ia i te 1966, 1970 me te 1974 Asian Games
He aha? I takaro ia i nga keemu 49 mo Japan tae noa ki te 1974.