2025 Middle & Long distance Triathlons in japan

New year, new (triathlon) season! Maybe even a new age group for some of you!

We've compiled a comprehensive list of triathlons taking place in 2025 that range from T100-style distances to the full long course triathlon - and everything in between. If there's one thing about middle distance triathlon in Japan, it's that there are no rules regarding distance. What that means is that swims may range from 2k to 4k; bikes from 70-something to 190; and the run might be from 18 to the full marathon.

Take note that some races, especially those in the second half of the year have only announced a tentative date. As per usual, the season starts in Okinawa in April and ends in Okinawa in November. Triathlons are scarce in July and August due to the heat and humidity of summer in Japan - it's a lot of liability for race organizers to bear (and you don't want to race in that, trust us!).

Keep in mind that many (but not all) triathlons require Japan Triathlon Union (JTU) membership to sign up. JTU membership is only available to residents of Japan. In recent years, some races have began to offer one-day memberships for an additional fee (typically 2-3,000 JPY). Whatever your circumstances are, contact us if you'd like to learn more about racing in Japan.

​(last updated Apr 24, 2025)

APRIL 
20 39th Miyakojima Triathlon (Okinawa) 

• S 3k, B 123k, R 35k
• Lottery Applications: Oct 1-31, 2024 (results Nov 22)

MAY
25 Nagaragawa Middle Triathlon 102 (Gifu)

• S 2k, B 80k, R 20k
• General Entry: Jan 23-Mar 30, 2025

25 Kasumigaura Triathlon Festa (Ibaraki) CANCELLED

• Middle (S 2.25k, B 71k, R 20k)
• Long (S 3k, B 116k, R 42k)
• General Entry: from Jan 4, 2025

JUNE
1 Sai no Kuni Triathlon in Kazo (Saitama)

• A (S 2.25k, B 72k, R 15k)
• B (1.5k, B 43k, R 10k)
• C (S 750m, B 21.6k, R 5k), Junior (S 200m, B 7.2k, R 2.5k)
• General Entry: Feb 8-May 10, 2025

8 Fukuyama Wakamachi Triathlon (Hiroshima)

• S 1.8k, B 80k, R 18k
• General Entry:  Feb 10-Apr 30, 2025

15 Goto Nagasaki International Triathlon (Niigata)

• A Type: S 3k, B 154.8k, R 42.2k
• B Type: S1.6k, B 101.7k, R 21.1k
• General Entry: Dec 20, 2024-Jan 31, 2025 (lottery)

29 38th Triathlon in Tokunoshima (Kagoshima)

• S 2k, B 75k, R 20k
• General Entry: Dec 2, 2024-Mar 31, 2025

​29 3rd Suwako 8Peaks Triathlon (Nagano)

• S 1.9k, B 66.2k, R 20k
• General Entry: Dec 20, 2024-Apr 30, 2025

29 4th Lake Biwa Triathlon (Shiga)

• S 1.9k, B 80k, R 20k (and Standard Distance)
• General Entry:  Feb 1-Mar 31, 2025

JULY
20 43rd Kaike Triathlon (Tottori)

• S 3k, B 140k, R 42.2k
• Lottery Applications: Mar 1-31, 2025 (results Apr 24)

6 31st Sendai Bay Shichigahama Triathlon (Miyagi)

• S 2.25k, B 55.3k, R 14.4k (and other distances)
• General Entry: Mar 6-Jun 15, 2025

AUGUST
24 Hokkaido Triathlon (Hokkaido)

• A Type: S 2k, B 137.1k, R 23.1k
• B Type: S 2k, B 91.9km R 23.1km
• General Entry: Jan 31-Jul 4, 2025

SEPTEMBER
7 Sado International Triathlon (Niigata)

• Type A: S 4k, B 190k, R 42.2k
• Type B: S 2k, B 108k, R 21.1k
• General Entry: from Feb 1, 2025 (lottery if registrations exceed capacity)
• Second Round: Apr 10-27, 2025

14 Irago Triathlon (Aichi)

• Type A: S 2.25k, B 70k, R 18k
• Type B: S 1.5k, B 42k, R 10k
• General Entry: Mar 29-May 7, 2025

14 IRONMAN Japan South Hokkaido (Hokkaido)

• S 3.8k, B 180k, R 42.2k
• General Entry: from Dec 16, 2024

27 12th Kujukuri Triathlon (Chiba)

• S 1.9k, B 90k, R 21k (and Standard)
• General Entry:  Mar 14-Aug 31, 2025

TBA 4th Nagaragawa Middle Triathlon 102 Autumn (Gifu)

• S 2k, B 71k, R 20k (and other distances)
• General Entry: TBA​

NOVEMBER 
16 2nd Okinawa Kin Triathlon (Okinawa)

• S 2k, B 70k, R 22k
• General Entry: May 1-Jun 30, 2025

23 38th Izena 88 Triathlon (Okinawa)

• S 2k, B 66k, R 20k
• General Entry: TBA