Mountain Freestone · Volcanic · Honshū, JP

Azusa River (Kamikōchi)

Japan Alps river

The Azusa rises at the heart of the Japanese Alps at Kamikōchi, a valley of such beauty that it is protected and walked by thousands, and through it the river runs gin-clear over pale stones beneath the Hotaka peaks.

Tomorrow · Not the day for it
Sculpin Streamer
Forecast · Tomorrow
Not the day for it
Not much stacked in your favour today. Worth an hour if you are nearby, not worth the special trip.
45% projected
Today's fly
Sculpin Streamer
Sculpin Streamer
Conditions on the water · Tomorrow
Estimate
Level
Very heavy rain recently
No gauge reading
Water temp12.6°C
ClarityUnfishable
Weather17°C
WindN 6 km/h
Pressure1026 hPa
Rain · recent57.6 mm
Rain · ahead16.7 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

Water temperature for Rainbow Trout
Ideal
13°C est.ideal 1018°C
0°14°28°
How to fish it · for Rainbow Trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Why this works
Poor water temperature is working for you, but water clarity is the limiting factor today.
Hatch timeline · tomorrowPeak at 2pm

12pm(now) Himalopsyche japonica

Stage: Taking dunsApproach: Dry flyActivity: 47%
Also:Daddy Long Legs45%Heather Fly45%Autumn Olive32%
Peak emergence windowWeather boost12 food groups active

Peak activity at 2pmAutumn Dun (Autumn Dun, Weather boost)

Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 2 as a supporter.

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Evidence
ModelledModerate confidence

Modelled from regional ecology — no survey or occurrence data for this water yet.

Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Stenopsyche CaddisHatch
2
3
3
2
Cicada (Semi)Hatch
2
2
Ephemera strigata (Mid-Reach Keiryu Mayfly)Hatch
2
3
3
3
2
Epeorus latifolium (Riffle Mayfly)Hatch
2
3
3
3
3
3
2

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Rainbow Trout fly box
Permits & access
Permit required — see local rules.
  • Kamikōchi is protected; local co-operative rules and a yugyoken apply, with access and method limits
  • Confirm before fishing.
What's coming
Plan ahead
5-day outlook
Other water nearby · 2
Gallery · 2
  1. Japan Alps river
    Alpine river through UNESCO-protected Kamikōchi.
  2. Terrain map of the venue
    Terrain map
About this water

The Azusa rises at the heart of the Japanese Alps at Kamikōchi, a valley of such beauty that it is protected and walked by thousands, and through it the river runs gin-clear over pale stones beneath the Hotaka peaks. It holds iwana and stocked rainbows in cold alpine water, and it is as much a pilgrimage to a landscape as a fishing trip — tenkara country in the truest sense.

Under the surface

A clear alpine river at the roof of Honshū, running off the Hotaka and Yari peaks through the protected valley of Kamikōchi over pale volcanic stone. Iwana hold in the cold pockets; the water is as much sacred landscape as fishery, and the native fixed-line tenkara belongs here.

Wading: Cold alpine water, protected park rules, altitude

  • River
  • Volcanic
  • Confined
  • Pool riffle
  • Pocket water
Conservation note

White-spotted char (iwana), yamame, and stocked rainbow. Iwana and yamame are the wild natives.

The full read · show the working · for Rainbow Trout · confidence 55%
How the 20 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow40 × 22%8.8
Clarity10 × 18%1.8
Feeding Time60 × 13%7.8
Pressure75 × 7%5.3
Insect activity64 × 12%7.7
Limiting factor: Water is unfishable — too coloured for Rainbow Trout= 59
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
A drop and clear would lift the flow and clarity scores.
The dawn and dusk windows score higher than the midday lull.
Directions
Seasons & zones
  • Char late February to Aprillate September to mid-October

    Honshu/Shikoku/Kyushu keiryu are managed by local fishery co-operatives — a yugyoken (day/annual ticket) is required, and most streams close around 30 September / mid-October for spawning. Species are surfaced in prose only (no engine slugs for yamame, amago or iwana). Legal status: guidance_not_permission.

Related guides
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