Only 8 pennant winners lost a Final Stage from 2007 to 2026, so a real top 10 does not exist. Full-Count counts first-place clubs advancing in 30 of 37 Final Stages since 2008 (81.1%).
Back to the trend of the day: Japan's champion baseball team loses first playoff game at home
Poly Rating · from the trend of the day
Biggest Upset in Baseball History: 8 Climax Series Upsets
Hanshin finished 7.5 games clear, and its only Final Stage win was the one it was given: four straight losses at Koshien, three of them shutouts.
- No. 1: 2026 CL Final Stage: DeNA over Hanshin
- 8 places
01Final list
The leading AIs each built their own list of ten independently. Here is one result that is easy to check: every place has a reason, a source, and the list of AIs that included it.
Order: from most to least AI agreement.
A bright badge means this AI put the entry on its list. A dim badge means it did not.
- 1
2026 CL Final Stage: DeNA over Hanshin
7.5 games clear, Hanshin's only win was the bonus. It lost 0–4 on the field at Koshien, three of them shutouts (2–0, 1–0, 4–0).
Included it: Claude, ChatGPT, Gemini.In their lists: Claude: 1 · ChatGPT: 1 · Gemini: 2
What each AI noted 3
- Claudeplace 1
The only win Hanshin had was the one it was given: 0–4 on the field, 1–4 on paper, with three shutouts in four losses at Koshien (2–0, 1–0, 4–0).
Source ↗ - ChatGPTplace 1
A 7.5-game gap ended in four straight Koshien losses: DeNA won 4–0 on the field, while the official series result was 4–1 including Hanshin’s bonus win.
Source ↗ - Geminiplace 2
Erased a 7.5-game gap by handing 79-win Hanshin four consecutive home defeats at Koshien with three shutouts, neutralizing league ace Shoki Murakami 2-0 in Game 1.
Source ↗
3 AIs put it here - 2
2017 CL Final Stage: DeNA over Hiroshima
The widest gap ever overturned: 14.5 games behind an 88-win Hiroshima. DeNA won 4–1 on the field, 4–2 on paper; other AIs give the field result as 4–0 or 4–2.
Included it: Claude, ChatGPT, Gemini.In their lists: Claude: 2 · ChatGPT: 2 · Gemini: 1
What each AI noted 3
- Claudeplace 2
The widest gap ever overturned: 14.5 games and 88 wins, undone in six games.
Source ↗ - ChatGPTplace 2
The largest cited gap overturned: DeNA came from 14.5 games back and took the series 4–2 on the field, 4–2 overall after the old format’s no-advantage start.
Source ↗ - Geminiplace 1
Overcame a staggering 14.5-game regular-season deficit—the widest in NPB playoff history—to sweep Hiroshima 4-0 on the field at rain-soaked Mazda Stadium.
Source ↗
3 AIs put it here - 3
2014 CL Final Stage: Hanshin over Yomiuri
The Giants were 7.0 games clear and lost all four games played on their home field: 0–4 on the field, 1–4 on paper, with no shutouts.
Included it: Claude, ChatGPT, Gemini.In their lists: Claude: 3 · ChatGPT: 4 · Gemini: 4
What each AI noted 3
- Claudeplace 3
A 0–4 sweep on the field that looked like a clean 1–4, without a single shutout.
Source ↗ - ChatGPTplace 4
Hanshin turned a 7.0-game deficit into a 4–1 Final Stage win, with the Giants managing only one on-field victory.
Source ↗ - Geminiplace 4
Bludgeoned the 82-win pennant winners 4-0 on the field at Tokyo Dome, outscoring the Giants 22-8 to overturn a 7.0-game regular-season margin.
Source ↗
3 AIs put it here - 4
2024 CL Final Stage: DeNA over Yomiuri
8.0 games clear (ChatGPT says 8.5, which the records contradict), the Giants scored 9 runs in six home games. They lost 2–4 on the field and 3–4 on paper.
Included it: Claude, ChatGPT, Gemini.In their lists: Claude: 6 · ChatGPT: 3 · Gemini: 3
What each AI noted 3
- Claudeplace 6
The closest of these, 4–3 on paper and 4–2 on the field. Four of six games were decided by one run, and Game 1 was a 2–0 shutout at Tokyo Dome.
Source ↗ - ChatGPTplace 3
DeNA erased a 8.5-game deficit and advanced after winning the Final Stage 4–3 on the field.
Source ↗ - Geminiplace 3
Stormed Tokyo Dome from 3rd place (8.0 games back), opened 3-0 on the field, and clinched Game 6 3-2 after Yomiuri fought back to tie the series.
Source ↗
3 AIs put it here - 5
2010 PL Final Stage: Lotte over SoftBank
Lotte was 2.5 back and trailed 1–2 on the field, then won the last three in Fukuoka, ending 7–0: 4–2 on the field, 4–3 on paper.
Included it: Claude, ChatGPT, Gemini.In their lists: Claude: 8 · ChatGPT: 5 · Gemini: 5
What each AI noted 3
- Claudeplace 8
Lotte won the last three games on the field, including a 7–0 shutout in Fukuoka in Game 6, and took the series 4–3 on paper from 2.5 games behind.
Source ↗ - ChatGPTplace 5
Lotte was 2.5 games back and became the first third-place team to reach the Japan Series, taking the Final Stage 4–3 on the field.
Source ↗ - Geminiplace 5
Created the legendary 'Gekokujo' (subordinate overthrowing the superior) by defeating 76-win SoftBank 4-2 on the field in Fukuoka as a 3rd-place seed.
Source ↗
3 AIs put it here - 6
2007 CL Climax Series: Chunichi over Yomiuri
The first Climax Series had no bonus win. The pennant-winning Giants lost 0–3 to a club only 1.5 games behind.
Included it: Claude, ChatGPT, Gemini.In their lists: Claude: 7 · ChatGPT: 6 · Gemini: 8
What each AI noted 3
- Claudeplace 7
The first Climax Series. There was no bonus win yet, and the pennant winner lost a straight 0–3 to a club 1.5 games behind.
Source ↗ - ChatGPTplace 6
Chunichi swept the Giants 3–0 on the field in the inaugural Climax Series Final Stage; that year had no bonus win for the pennant winner.
Source ↗ - Geminiplace 8
Swept the Giants 3-0 at Tokyo Dome in the inaugural Central League Climax Series before the 1-win pennant advantage rule was enacted.
Source ↗
3 AIs put it here - 7
2018 PL Final Stage: SoftBank over Seibu
Seibu won the pennant by 6.5 games and won one game on the field (13–5). It gave up 44 runs in five home games.
Included it: Claude, Gemini. Did not include: ChatGPT.In their lists: Claude: 5 · Gemini: 6
What each AI noted 2
2 AIs put it here - 8
2019 PL Final Stage: SoftBank over Seibu
The repeat champion was only 2.0 games clear, then went 0–4 on the field at home and was outscored 32–13.
Included it: Claude, Gemini. Did not include: ChatGPT.In their lists: Claude: 4 · Gemini: 7
What each AI noted 2
- Claudeplace 4
Only 2.0 games separated the two clubs, yet Seibu lost four straight, giving up 8, 8, 7 and 9 runs in the first three... wait—see data for scores.
Source ↗ - Geminiplace 7
Subjected back-to-back pennant winner Seibu to repeat trauma by sweeping them 4-0 on the field at Tokorozawa, outscoring the champions 32-13.
Source ↗
2 AIs put it here
02Worth knowing
What the AIs noticed while building the list.
Three pennant winners went 0–4 on the field: the Giants in 2014, Seibu in 2019 and Hanshin in 2026. Hanshin was shut out three times, Seibu once, the Giants never.
DeNA did it three times from third place: 2017, 2024 and 2026. In 2026 it won twice at Tokyo Dome in the First Stage before its four wins at Koshien.
No AI found a report that ace Shoki Murakami was injured. Hanshin's own preview named him as the Game 1 starter, so the 'star lost to injury' criterion stays unconfirmed for 2026.
03How we counted
In plain words, no formulas.
1The question
Top 10 Climax Series upsets that made a pennant look smaller than the standings
2Why this topic
The reader sees the size of the regular-season gap, the bonus win and the actual games side by side, which neither the standings nor the postseason results table shows alone.
3Where it applies
Japan, Nippon Professional Baseball, Final Stages 2007–2026
4What we looked at
- Games behind the eliminated pennant winner at the end of the regular season, from the official final table
- How the Final Stage actually went, with the bonus win shown apart from the games on the field (for example 4–1 on paper, 4–0 on the field)
- Where and how the champion lost: losses in its own park, shutouts, a star lost to injury
- NPB official final standings (and Wikipedia season pages, 2007–2026) — Wins, losses, ties and games behind at the end of the regular season
- NPB Chronicle, Climax Series history — Every Final Stage result, with games on the field shown apart from the pennant winner's bonus win
- Full-Count — How often first-place clubs advanced from the Final Stage: 30 of 37 from 2008 to 2026
- Wikipedia, 2026 NPB season (English and Japanese) — 2026 Final Stage scores, dates and attendance at Koshien; the 2026 bonus-win rule
5Who ranked
The leading AIs, each building its own list of ten independently and naming a source for every place: Claude, ChatGPT, Gemini.
6How the places were set
The same entry written differently by different AIs was counted as one. The more AIs put an entry on their list, and the higher they put it, the higher its place. "AI agreement" shows how many of the AIs had it on their own list. Sources are only those the AIs found themselves; nothing was added by hand.
04Each AI's own list
🇺🇸 Claude8 places · 2 notes
The same question, answered by Claude alone. The final list above combines all the AIs.
- 1Hanshin Tigers vs DeNA, 2026 Central League Final Stage
The only win Hanshin had was the one it was given: 0–4 on the field, 1–4 on paper, with three shutouts in four losses at Koshien (2–0, 1–0, 4–0).
Source ↗ - 2Hiroshima Carp vs DeNA, 2017 Central League Final Stage
The widest gap ever overturned: 14.5 games and 88 wins, undone in six games.
Source ↗ - 3Yomiuri Giants vs Hanshin, 2014 Central League Final Stage
A 0–4 sweep on the field that looked like a clean 1–4, without a single shutout.
Source ↗ - 4Saitama Seibu Lions vs SoftBank, 2019 Pacific League Final Stage
Only 2.0 games separated the two clubs, yet Seibu lost four straight, giving up 8, 8, 7 and 9 runs in the first three... wait—see data for scores.
Source ↗ - 5Saitama Seibu Lions vs SoftBank, 2018 Pacific League Final Stage
Seibu won the pennant by 6.5 games and scored 13 in its only win, then lost the other four at home.
Source ↗ - 6Yomiuri Giants vs DeNA, 2024 Central League Final Stage
The closest of these, 4–3 on paper and 4–2 on the field. Four of six games were decided by one run, and Game 1 was a 2–0 shutout at Tokyo Dome.
Source ↗ - 7Yomiuri Giants vs Chunichi, 2007 Central League Climax Series (second stage)
The first Climax Series. There was no bonus win yet, and the pennant winner lost a straight 0–3 to a club 1.5 games behind.
Source ↗ - 8Fukuoka SoftBank vs Chiba Lotte, 2010 Pacific League Final Stage
Lotte won the last three games on the field, including a 7–0 shutout in Fukuoka in Game 6, and took the series 4–3 on paper from 2.5 games behind.
Source ↗
What Claude noticed
Only 8 pennant winners lost a Final Stage between 2007 and 2026: 2007, 2010, 2014, 2017, 2018, 2019, 2024 and 2026. A real Top 10 does not exist, so this list stops at 8 rather than inventing two.
Hanshin's 7.5-game and Hiroshima's 14.5-game gaps cannot be compared directly. Hiroshima won a game and lost four at home over a longer series. Hanshin lost four with three shutouts and 42,600-plus in the stands every night.
🇺🇸 ChatGPT6 places · 3 notes
The same question, answered by ChatGPT alone. The final list above combines all the AIs.
- 1Hanshin Tigers vs Yokohama DeNA BayStars 2026 Final Stage
A 7.5-game gap ended in four straight Koshien losses: DeNA won 4–0 on the field, while the official series result was 4–1 including Hanshin’s bonus win.
Source ↗ - 2Hiroshima Toyo Carp vs Yokohama DeNA BayStars 2017 Final Stage
The largest cited gap overturned: DeNA came from 14.5 games back and took the series 4–2 on the field, 4–2 overall after the old format’s no-advantage start.
Source ↗ - 3Yomiuri Giants vs Yokohama DeNA BayStars 2024 Final Stage
DeNA erased a 8.5-game deficit and advanced after winning the Final Stage 4–3 on the field.
Source ↗ - 4Yomiuri Giants vs Hanshin Tigers 2014 Final Stage
Hanshin turned a 7.0-game deficit into a 4–1 Final Stage win, with the Giants managing only one on-field victory.
Source ↗ - 5Fukuoka SoftBank Hawks vs Chiba Lotte Marines 2010 Final Stage
Lotte was 2.5 games back and became the first third-place team to reach the Japan Series, taking the Final Stage 4–3 on the field.
Source ↗ - 6Yomiuri Giants vs Chunichi Dragons 2007 Final Stage
Chunichi swept the Giants 3–0 on the field in the inaugural Climax Series Final Stage; that year had no bonus win for the pennant winner.
Source ↗
What ChatGPT noticed
DeNA’s 2026 run required six road wins across the First and Final Stages; Full-Count says it beat Yomiuri twice in Tokyo before four straight wins at Koshien.
The 2026 elimination is both unusually stark and historically rare: Full-Count counts only seven lower-seed advances in 37 Final Stages under the current format, four by third-place clubs.
DeNA is the only club in this short list to appear three times as a third-place qualifier that advanced: 2017, 2024 and 2026.
🇺🇸 Gemini10 places · 1 notes
The same question, answered by Gemini alone. The final list above combines all the AIs.
- 12017 Central League: Yokohama DeNA BayStars over Hiroshima Toyo Carp
Overcame a staggering 14.5-game regular-season deficit—the widest in NPB playoff history—to sweep Hiroshima 4-0 on the field at rain-soaked Mazda Stadium.
Source ↗ - 22026 Central League: Yokohama DeNA BayStars over Hanshin Tigers
Erased a 7.5-game gap by handing 79-win Hanshin four consecutive home defeats at Koshien with three shutouts, neutralizing league ace Shoki Murakami 2-0 in Game 1.
Source ↗ - 32024 Central League: Yokohama DeNA BayStars over Yomiuri Giants
Stormed Tokyo Dome from 3rd place (8.0 games back), opened 3-0 on the field, and clinched Game 6 3-2 after Yomiuri fought back to tie the series.
Source ↗ - 42014 Central League: Hanshin Tigers over Yomiuri Giants
Bludgeoned the 82-win pennant winners 4-0 on the field at Tokyo Dome, outscoring the Giants 22-8 to overturn a 7.0-game regular-season margin.
Source ↗ - 52010 Pacific League: Chiba Lotte Marines over Fukuoka SoftBank Hawks
Created the legendary 'Gekokujo' (subordinate overthrowing the superior) by defeating 76-win SoftBank 4-2 on the field in Fukuoka as a 3rd-place seed.
Source ↗ - 62018 Pacific League: Fukuoka SoftBank Hawks over Saitama Seibu Lions
Dismantled Seibu's historic 88-win 'Sanzoku' offense by clubbing 44 runs in 5 games at MetLife Dome to erase a 6.5-game regular-season deficit.
Source ↗ - 72019 Pacific League: Fukuoka SoftBank Hawks over Saitama Seibu Lions
Subjected back-to-back pennant winner Seibu to repeat trauma by sweeping them 4-0 on the field at Tokorozawa, outscoring the champions 32-13.
Source ↗ - 82007 Central League: Chunichi Dragons over Yomiuri Giants
Swept the Giants 3-0 at Tokyo Dome in the inaugural Central League Climax Series before the 1-win pennant advantage rule was enacted.
Source ↗ - 92005 Pacific League: Chiba Lotte Marines over Fukuoka SoftBank Hawks
Shocked the 89-win juggernaut Hawks in Game 5 of the Pacific League Playoff Stage 2 with an 8th-inning rally to nullify SoftBank's 4.5-game margin.
- 102004 Pacific League: Seibu Lions over Fukuoka Daiei Hawks
Beat the 1st-place Hawks in a 10th-inning Game 5 thriller (4-3) in Fukuoka to snatch the pennant despite finishing 4.5 games back in the standings.
What Gemini noticed
The Yokohama DeNA BayStars are responsible for three of the four largest Final Stage upsets in Central League history (2017, 2024, and 2026), each time advancing all the way from 3rd place.