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.

Today · Not the day for it
Pheasant Tail nymph
Forecast · Today
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
Pheasant Tail nymph
Pheasant Tail nymph
Conditions on the water · Today
Estimate
Level
Very heavy rain recently
No gauge reading
Water temp5.1°C
ClarityUnfishable
Weather10°C
WindN 4 km/h
Pressure1013 hPa
Rain · recent58.3 mm
Rain · ahead4.2 mm

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

Water temperature for Rainbow Trout
Cool — slow
5°C est.ideal 10–18°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 — barometric pressure is working for you, but water clarity is the limiting factor today.
Hatch timeline · todayQuiet day

Low insect activity predicted today

Sub-surface · on the nymphunder the surface

Hatch predictions

Supporters see the full sub-surface read.

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Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Supporters see what else is on the menu.

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Evidence
Records-basedModerate confidence

Based on species-occurrence records, not local invertebrate surveys.

Through the year
0–3 scale · October 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
Fishing better nearby · 1
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 45%
How the 20 is built — score × weight = contribution
Temperature29 × 28%8.1
Flow28 × 22%6.2
Clarity10 × 18%1.8
Feeding Time40 × 13%5.2
Pressure75 × 7%5.3
Insect activity37 × 12%4.4
Limiting factor: Water is unfishable — too coloured for Rainbow Trout= 31
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
What would change the calculation
Warmer water — toward the 10–18 °C ideal band — would lift the temperature score.
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 April → late 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
Booking & contacts