viewed as one of the top high school pitchers in the country, Sato pitched well in the regional Miyagi Tournament that summer, throwing 226 pitches in fifteen shutout innings in the finals against rival Tohoku High School on 31 July in what ended in a scoreless tie (as per tournament regulations). He started the rematch that ensued the next day (1 August), throwing 148 pitches while holding Tohoku High to two runs in a 6–2 complete game win and leading the school to a third straight appearance in a national tournament. Sato took the mound against Chiben Gakuen Wakayama Senior High School in the first round of the 89th National High School Baseball Championship that followed on 9 August, holding the team to just two runs while striking out 17 in a 4–2 complete-game win. While he gave up a home run to junior and noted cleanup hitter Masaki Sakaguchi (currently a third baseman for Tokai University) in the sixth inning, he threw a pitch that the radar gun at Koshien Stadium clocked at in Sakaguchi's next at-bat in the eighth, tying the highest speed ever recorded in the tournament (since the radar gun began being used in 1980) marked by current Yokohama BayStars right-hander Hayato Terahara as a senior for Nichinan Gakuen High School in 2001. He struck Sakaguchi out looking in that at-bat, throwing a total of 19 pitches clocked at or above in the same game. In the fourth inning of the second-round game against Chiben Gakuen Senior High School (the Nara champions) on 15 August, Sato threw a pitch clocked at , setting a new tournament record for pitch speed (as per official stadium radar gun readings). He gave up five runs in the very next inning, however, allowing eight hits and five walks in a 5–2 complete game loss. While he made three appearances in national tournaments during his three-year high school career, he never succeeded in getting past the second round. Sato was chosen to play in the U.S.−Japan High School Baseball Tournament (organized by the Japanese Educational Resource Center in conjunction with the Major League Baseball Urban Youth Academy) as a member of the Japanese team later that summer, clocking a new personal-high during the tournament. Sato was one of the most highly touted players going into the 2007 NPB high school draft, attracting the attention of scouts for not only his fastball