Rina Hatachi: Japan's Two-Time EGMO Gold Medallist

Biography

The two gold medals

EGMO publishes a scoreboard for each edition that lists every contestant by national code, with her marks on six problems, her total, her rank and her medal. Hatachi appears on two of them under Japan.

In Prishtina in 2025 she scored 30 points and placed twelfth. In Bordeaux in 2026 she scored 26 and moved up to joint tenth. Both results carry gold, and the second is the more telling, because it came against a new field and six new problems. The scoreboard sets out her marks on each of those problems, which is as close to a narrative of the two mornings as the public record gets.

A European olympiad with a global field

The competition's name describes its origin rather than its guest list. Hatachi's entries sit on the same scoreboards as teams from outside Europe, and the 2023 edition makes the point plainly: among the fourteen contestants who scored a perfect 42 that year were competitors listed for Australia, China and the United States alongside European names.

That matters for reading a Japanese contestant's placing. A top-ten finish at EGMO is not a regional ranking but a placing against many of the strongest school-age mathematicians competing anywhere that spring.

The tie at the top ten

The 2026 scoreboard shows three contestants level on 26 points and therefore sharing tenth place: Hatachi for Japan, Anna Kazhamiakina for Italy and Defne Hergul for Turkey. All three were awarded gold.

Ties of this kind are a structural feature rather than a coincidence. Totals are assembled from six problems marked out of seven, so the arithmetic produces a small number of possible scores and the table clusters tightly around the medal boundaries.

What is documented - and what is not

This page is built from two official scoreboards and a third consulted for context. They record a name, a country, six problem scores, a total, a rank and a medal, and they record nothing else.

No birth year, age, school, city, photograph or quotation has been published in the sources used here, and no Wikipedia article on Rina Hatachi was found. Those gaps are reported rather than filled. Where a competitor is a minor, the absence of detail is part of the record and is treated as such.

Why repeat golds are rare

The olympiad relocates annually, with the editions documented here staged in Portoroz in Slovenia, Tskaltubo in Georgia, Prishtina in Kosovo and Bordeaux in France. Each brings a fresh problem set written for that year, so nothing carries over except the contestant's own preparation.

A returning competitor must be selected again by her national team and then repeat the performance under different conditions. Hatachi did it and improved her placing while doing so, from twelfth to joint tenth, which is the part of the record that a single score cannot show.

Achievement Timeline

Rina Hatachi — every milestone on this page, in order.

2025

Wins EGMO gold in Prishtina with 30 poWins EGMO gold in Prishtina with 30 points, twelfth place (EGMO official scoreboard)

2026

Wins EGMO gold in Bordeaux with 26 poiWins EGMO gold in Bordeaux with 26 points, joint tenth (EGMO official scoreboard)

2026-09

No later result, profile or public staNo later result, profile or public statement appears in the sources used here

Historical Comparison

Person	Country	Milestone	Age / Stat
Rina Hatachi	Japan	EGMO gold medals in 2025 and 2026	—
Colin Shanmo Tang	United States	A perfect 42/42 at the International Mathematical Olympiad, 2019	—
Youngjun Cho	South Korea	A perfect 42/42 at the International Mathematical Olympiad, 2019	—
Galiia Sharafetdinova	Russia	A perfect 42/42 at the International Mathematical Olympiad, 2022	—
Ihor Pylaiev	Ukraine	A perfect 42/42 at the International Mathematical Olympiad, 2022	—

What is documented — and what is not

✓ Documented

Gold medal and 30 points, twelfth place, at EGMO 2025 in Prishtina (EGMO official scoreboard)
Gold medal and 26 points, joint tenth, at EGMO 2026 in Bordeaux (EGMO official scoreboard)
Listed under Japan on both scoreboards

? Unverified, disputed or wrong

No published age, birth year, school or home city
No Wikipedia article, interview or press coverage located
No information about her results before 2025 or after 2026

Questions people ask about Rina Hatachi

What is Rina Hatachi known for?

Winning gold at the European Girls' Mathematical Olympiad for Japan in both 2025 and 2026.

How old is Rina Hatachi?

No source used here gives an age or birth year. The EGMO scoreboards do not record dates of birth.

Can Japanese contestants compete at a European olympiad?

The scoreboards list her under Japan, and the competition's results include teams from outside Europe. In 2023, contestants listed for Australia, China and the United States were among those who scored a perfect 42.

What were her EGMO scores?

30 points out of 42 in 2025, for twelfth place, and 26 points in 2026, for joint tenth. Both results carried gold medals.

Who shared her 2026 rank?

Anna Kazhamiakina of Italy and Defne Hergul of Turkey, both on 26 points and both awarded gold.

Is Rina Hatachi on Wikipedia?

No Wikipedia article on her was found. Her documented record consists of the official EGMO scoreboards.

Where does Rina Hatachi study?

No source used here names a school, a university or a home city.

Where is Rina Hatachi now?

Nothing after the 2026 olympiad appears in the sources used here.

Quick quiz: how well do you know Rina’s story?

Which country does Rina Hatachi compete for?

How did her EGMO placing change between 2025 and 2026?

How many problems are set at EGMO?

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Sources

EGMO 2025 scoreboard (Prishtina, Kosovo) — European Girls' Mathematical Olympiad (official), 2025-04
EGMO 2026 scoreboard (Bordeaux, France) — European Girls' Mathematical Olympiad (official), 2026-04
EGMO 2023 scoreboard (Portoroz, Slovenia) — European Girls' Mathematical Olympiad (official), 2023-04

Checked by the Geniuses.club editorial team. Ages are given as of September 2026.