Ryota Oishi broke a 2-2 tie with a fourth-inning RBI triple as Yokohama went on to beat last year's runnerup, Koryo of Hiroshima Prefecture, 7-4 in the second round of the National High School Championship on Tuesday.
Yokohama took a 4-2 lead in the fourth and Koichiro Matsumoto and Yoshitomo Tsutsugo knocked in one run apiece with a triple and a single in the sixth, respectively.
In other second-round action at Koshien Stadium, Mao Morikawa singled in the game-winning run in the bottom of the 10th inning as Osaka Toin edged Ishikawa's Kanazawa 6-5.
Sendai Ikuei advanced to the third round for the first time in 12 years as Shota Ogawa broke a fifth-inning tie with a two-run triple in a 6-4 victory over Fukui Shogyo.