79th AICHI PREFECTURAL HIGH SCHOOL SWIMMING COMPETITION
- Saturday, June 21st & Sunday, June 22nd
- Aquarena Toyohashi, Toyohashi City, Aichi Prefecture
- LCM (50m)
- Results
While Japanese teenager Shin Ohashi is wreaking havoc in the men’s breaststroke events this weekend, another 16-year-old did damage in the 400m IM.
Competing at the 79th Aichi Prefectural High School Swimming Competition, fellow 16-year-old Yumeki Kojima blasted a new lifetime best of 4:11.67 to take the gold and beat the field by over 20 seconds.
Kojima’s previous career-swiftest performance entering this two-day competition sat at the 4:17.42 he notched at last year’s Japanese High School Championships. That means he hacked nearly 6 seconds off his previous PB en route to becoming Japan’s 10th-best performer of all time.
Splits for Kojima’s 4:11.67 are below.
Japanese Men’s Top 10 LCM 400 IM Performers All-Time
- Kosuke Hagino – 4:06.05, 2016
- Daiya Seto – 4:06.09, 2020
- Tomoyuki Matsushita – 4:08.61, 2025
- Asaki Nishikawa – 4:09.63, 2025
- Kosuke Makino – 4:09.19, 2025
- Tomoru Honda – 4:09.98, 2023
- Yuya Horihata – 4:10.52, 2012
- Takeharu Fujimori – 4:10.90, 2017
- Kaito Tabuchi – 4:11.15, 2024
- Yumeki Kojima – 4:11.67, 2025
The teen checks in as Japan’s 4th-best performer of 2025, a year which has already seen Olympic silver medalist Tomoyuki Matsushita, Asaki Nishikawa and Kosuke Makino make dents in the nation’s all-time rankings.
In terms of the Japanese High School National Record, that remains at the 4:08.94 Olympic champion Kosuke Hagino put on the books at the 2012 Olympic Games.
For additional perspective, 16-year-old Kojima’s 4:11.67 performance would represent a new United States National Age Group Record, destroying the 4:14.73 Olympic medalist Carson Foster established in 2018. That overtook Olympic legend Michael Phelps‘ previous age group standard of 4:15.20 logged in 2001.
Kojima now ranks 12th in the world on the season.
2024-2025 LCM Men 400 IM
MARCHAND
4:04.73
| 2 | Bobby FINKE | USA | 4:07.46 | 06/05 |
| 3 | Carson Foster | USA | 4:07.92 | 06/06 |
| 4 | TOMOYUKI MATSUSHITA | JPN | 4:08.32 | 08/03 |
| 5 | Ilya Borodin | RUS | 4:09.16 | 08/03 |
| 6 | Yumeki Kojima | JPN | WJR 4:09.38 | 07/20 |
| 7 | ASAKI NISHIKAWA | JPN | 4:09.63 | 03/20 |
| 8 | Rex MAURER | USA | 4:09.65 | 06/05 |
| 9 | KOSUKE MAKINO | JPN | 4:09.79 | 03/20 |
| 10 | Wang Shun | CHN | 4:10.64 | 05/24 |
| 11 | Gasa Nishikawa | JPN | 4:10.80 | 06/07 |
| 12 | Raito Numata | JPN | 4:11.37 | 08/23 |
The teen will be competing at this year’s World Junior Championships. His time tonight would have rendered him the silver medalist at the 2023 edition of the championships.
In another article sometime brought up a “x country vs world” in a relay of any event.
Sounds like the Japanese men could take on the world in a 4x400im
EUA with foster, finke and maurer is pretty strong tough. If kalizs came back its over
Maybe they would beat any other single country in the event, but the top 3 in the world last year and top 3 in the world this year were not Japanese so it would be tough for Japan to get the win against the rest-of-the-world team.
Japan is just producing 200 Breast/400 IM specialists out of a factory at this point
Japan has to be #2 with most swimmers under the 4:10 barrier?
How????
I wonder if these teenagers will stay around?
I hope so.
I have seen numerous very fast swims from young Japanese swimmers at QLD Championships over the years but then they seem to disappear. This though is another level.
If my math is correct the partials were 57/1:05/1:10/59
Crazy breast split for a 16 years old, the same as phelps in his peak
Correct me if I’m wrong, but does Japan now have TWO 16 year olds who are 4:12/4:11?! First Numata and now Kojima. Their juniors have been on a tear lately!
There should be more comments here this is insane
I think people are burned out on young Japanese swimmers who drop insane times and then never really do much after that. More of a wait and see attitude now.
I think it’s more there was other news today…
People seemed to not want to do much today, vibes were off