People · Japan
Katsumi Seino (清野克己)
Megaminx · top 1.2% of 34,786 all-time · competing since August 2022 · 2022SEIN01
Katsumi Seino (清野克己) has been competing for 4 years. His best event is the Megaminx: a personal-best single of 38.15, set at Kansai Mega Day 2025, puts him in the top 1.2% of the 34,786 people who have ever been ranked in the event, and 8th in Japan. Until November 2014, no official Megaminx solve in the world had been that fast. Across 6 competitions since August 2022, he has put 110 official solves on the record across five events. Solve to solve, his 3×3 times vary about 17% around a typical one; 96% of the 35,811 competitors with ten or more counted rounds hold a tighter spread. Katsumi has entered six competitions, more competitions than 86% of everyone who has ever competed.
Standing, event by event
vs everyone ever ranked| Event | PB single | PB average | All-time standing | Japan | |
|---|---|---|---|---|---|
| Megaminx | 38.15 | 44.58 | top 1.2% | 8 / 313 | |
| 3×3 | 8.29 | 10.23 | top 3.3% | 139 / 3,329 | |
| 5×5 | 1:11.68 | 1:22.02 | top 12.8% | 78 / 420 | |
| 3×3 one-handed | 21.47 | 26.04 | top 24.5% | 197 / 529 | |
| Skewb | 7.42 | 9.48 | top 36.9% | 180 / 338 |
Percentile against all competitors ever ranked in each event, a fairer measure than raw rank, because the pools differ by a factor of ten.
The line so far
Best single per competition, 3×3. Faster is higher — the axis is the right way up.
The story so far
- 28 Aug 2022First competition: Yoga Summer B 2022. A 10.33 3×3 single to start from.
- 28 Aug 2022First sub-10 3×3: 9.11 at Yoga Summer B 2022.
Competitions
- Kansai Mega Day 2025 · 2 Nov 2025 — 2 personal bests set
- Tokai Summer 2025 · 27 Jul 2025
- Hiroshima Winter 2024 · 10 Feb 2024
- Rubik's WCA World Championship 2023 · 12 Aug 2023 — 1 personal best set
- Hiroshima Spring 2023 · 25 Mar 2023 — 1 personal best set
- Yoga Summer B 2022 · 28 Aug 2022 — 2 personal bests set
Reading this page: a single is one solve's time · an average is the middle three of five solves, best and worst discarded · a PB is a personal best · a DNF (did not finish) is an attempt with no valid result: a popped piece, an unsolved face, an over-limit memorisation · top X% compares against everyone ever ranked in that event, which is fairer than raw rank because event pools differ tenfold.
The circuit
The people whose scorecards keep turning up next to his.
- Tomohiro Kobayashi (小林知広) — met in 21 rounds, finished ahead 4 times
- Yuki Nomura (野村優希) — met in 20 rounds, finished ahead 6 times
- Daisuke Kochi (幸地大輔) — met in 17 rounds, finished ahead 16 times
Next targets
- A sub-30 Megaminx single — 75 people have one; it is 8.15 away.
- A sub-8 3×3 single — 7,931 people have one; it is 0.29 away.
Targets move as he improves.