The reason March Madness is the best event in American sports is a single word: upsets. Koshien runs on the same fuel. And the 2026 summer tournament delivered early, taking down half the field’s anointed favorites before the quarterfinals even arrived.

First, the favorites

Before a pitch was thrown, Japanese analysts gave their top “S” rating — reserved for genuine national-title contenders — to just four schools: Sendai Ikuei, Kanto Daiichi, Yokohama, and Riseisha. If you had to bet, you bet on those four.

By the middle rounds, two of them were already eliminated.

Upset 1: Kanto Daiichi, out in the first game

The earliest shock. Kanto Daiichi, one of the four S-rated favorites, lost its opening game to Eimei, 1–4 — no slow build, no dramatic collapse, just gone in a single afternoon. That’s the brutal math of single elimination: a favorite can be knocked out before it ever gets going, and one cold game ends the whole summer.

Upset 2: Mie takes down Riseisha

The signature giant-killing of the tournament. Riseisha — an Osaka powerhouse, another S-rated favorite, a school that reloads pro prospects every year — ran into Mie, and lost 2–5. The engine of the upset was Mie’s No. 10 left-hander, Seiyu Ueda, who threw five scoreless, walk-free innings to strangle one of the tournament’s most dangerous lineups. Mie reached its first quarterfinal in 12 years. We told the full giant-killing story here.

The heartbreak that wasn’t quite an upset

Not every stunning game produces an upset in the standings. Seirei Christopher’s ace Riku Takabe struck out ten and no-hit Sano Nichidai into the fifth inning — and lost 0–1, the only run scoring on a dropped fly ball. A dominant performance, a season-ending result. At Koshien, the two are never far apart.

Why it matters: the bracket blew open

With two of the four favorites gone, the tournament transformed. The safe bets were off the board, the survivors inherited a much friendlier path, and every remaining underdog could suddenly see a road to the final. That’s exactly why you can’t look away from single-elimination baseball played by teenagers: reputation and seeding buy you nothing once the game starts. Anyone can go home, and anyone can keep dreaming.

More: meet the favorites who survived · how to watch the rest from abroad · what is Koshien, explained.