Mezue ahịrịokwu na-esonụ: Yamaguchi gbara asọmpi dị ka onye dị afọ iri na asatọ na onye so n'òtù ndị Japan n'ihe omume abụọ nke ịgba ọsọ freestyle na 2008 Summer Olympics na Beijing. N'agbanyeghi na o nwetaghi ebe onye obula na 200 m freestyle, o jisiri ike tinye nke anọ na ule Olympic na Tokyo (2:01.64) iji nweta nhọrọ zuru oke na ndị otu relay. Ijikọ aka na Haruka Ueda, Maki Mita, na Emi Takanabe na
4 × 200 m freestyle relay final, Yamaguchi gbara ụkwụ nke abụọ na nkewa nke 1:58.51, mana ndị otu Japan ga-edozi maka ebe nke asaa na 7:57.56. Yamaguchi sonyekwara na 4 × 100 m freestyle relay, ya na Ueda, Mita, na Asami Kitagawa, mana ha hapụrụ nke ikpeazụ n'etiti ndị isi asatọ site na 0.08 nke abụọ na oge nke 3:39.25.