Hoshimachi‑sha

Tonight · Twilight session 19:40 · 3 seats left

Achi Village · Nagano · Japan’s No. 1 starry sky

The hillside hut that waits for the stars. Two guided sessions a night — twilight and late-night. Eight people. One guide. The whole sky.

Tonight on the bench 19:40·Twilight session·3 / 8 seats ·22:00·Late-night session·5 / 8 seats
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The Milky Way arching over a snow-covered ridge under a dark sky

· · · Weather gate: cloudy all day → session called by 17:00 the day before, full refund. 21:08 · Achi Village, JST

Section two · the night ledger

Two sessions, four seasons, one careful pace.

Each session is 90 minutes with Hoshino-san on the bench. Twilight begins when the last daylight leaves the western ridge; late-night starts after the sky fully darkens and the Milky Way swings overhead.

Twilight session

Sunset → astronomical dusk

  • 19:00 Spring Hanami, hanamomo bloom 3/8
  • 19:40 Summer Milky Way rising south-east 3/8
  • 18:20 Autumn Cool air, sharp skies 5/8
  • 17:50 Winter Orion & Sirius over 2/8

Late-night session

Astronomical dark → 23:30

  • 21:30 Spring Sagittarius climbing, Saturn in view 5/8
  • 22:00 Summer Galactic core at zenith 5/8
  • 21:00 Autumn Andromeda & the Pleiades 4/8
  • 20:30 Winter Star-heavy sky, very cold 2/8
Per person

¥7,500 adult · ¥4,500 through middle school. Amazake or cocoa on the bench is included.

90 min · capacity 8

Section two-bis · the moon ledger

The next thirty nights, written in shadow.

The phase below is computed from your real clock when the page loaded — refresh for today’s update. We watch for the new-moon window first; the waxing crescent in the week after is the Milky Way’s friend.

  • SMTWTFS

    ° new moon · Milky Way window ◐ waxing ◑ waning • full moon · crater walk

    Section three · what we see

    The sky decides the menu. We work with whatever is up.

    The plan on the chalk board changes the moment a thin moon rises, a planet swings into the eyepiece, or the Perseids light up the eastern ridge. These are the things we watch for across the year.

    Star trails circling above a sea of clouds over the ridge

    01 · Milky Way

    The galactic core

    From mid-July through early September, the Sagittarius arm rises out of the south-east after 22:00. On a moonless night the dust lane shows up to the naked eye; through the Dobsonian it looks like soft fog against the dark.

    Peak window Jul 20 – Sep 5

    02 · Planets & Moon

    Saturn, Jupiter, the lunar craters

    Saturn’s rings are usually the show-stopper in spring and autumn. When the moon is up, we point the twenty-centimetre Dobsonian at the terminator and walk the craters across the line where night meets day.

    Best for Full-moon nights

    03 · Meteor showers

    Perseids & Geminids

    Two showers worth losing sleep for. Perseids peak around 12 August with up to sixty meteors an hour at the radiant in the north-east. Geminids peak 13–14 December — slow, bright, often coloured, and visible from the bench in winter coats.

    Perseids Aug 12 · Geminids Dec 13

    04 · Star clusters

    Pleiades, the Beehive, M31

    The Pleiades are naked-eye even before dark-adapted. The Andromeda Galaxy is a faint smudge by eye and a clear disc through the scope on autumn nights. We will leave the light on, give your eyes twenty minutes, then look again.

    Best for Oct – Dec evenings

    05 · Aurora watch

    On the rare good night

    A geomagnetic storm can push the auroral oval south to central Japan a handful of times a decade. We will text everyone on the bench if the Kp index climbs above seven on a clear night. No promises, ever.

    Frequency 1–3 nights / decade

    06 · ISS & Iridium flares

    Pass overhead

    A handful of times a week the International Space Station crosses the Nagano sky. If the timing lines up with the session, we’ll point it out — a slow, bright, even moving dot, tracking east to west, no sound.

    Heads-up in the 5-min briefing

    Section three-bis · the annual ledger of falling stars

    Eight named showers worth losing sleep for.

    ZHR (zenithal hourly rate) is the count an experienced observer would see under a perfectly dark sky with the radiant overhead — what you actually see on the bench will be lower because Achi is at 36° N and the radiant is rarely at the zenith. These are the showers we plan the season around.

    Shower Peak Window ZHR Notes
    Quadrantids Jan 4Jan 1–6110 Sharp six-hour peak; cold, dark, long nights. Wrap up well.
    Lyrids Apr 22Apr 16–2518 Spring wind; occasional bright fireballs with persistent trains.
    &eta-Aquariids May 6Apr 19 —May 2850 Radiant low in the east before dawn; long-tailed, fast.
    Perseids Aug 12Jul 17 —Aug 24100 The big one. Warm bench, no thermals, family-friendly. We add a third peak night to the calendar.
    Orionids Oct 21Oct 2 —Nov 720 Slow, fine, often with a faint orange tint; peaks in two waves.
    Leonids Nov 18Nov 6–3015 Storms every 33 years (next: 2099). Otherwise quiet and fast.
    Geminids Dec 13Dec 4–17120 Slow, bright, colourful. The most reliable annual shower. Wool-blanket night.
    Ursids Dec 22Dec 17–2510 Quiet winter coda; for the sleepless on the bench the night before.
    The warm-lit wooden hillside cabin where groups gather before stepping out under the stars
    Hoshimachi-sha · the bench outside the cabin door

    Section four · the cabin

    A small wooden cabin on the slope above Hirugami Onsen, with red lights inside and the dark twenty steps away.

    Hoshino-san built the cabin in 2014 and moved his 20-cm Dobsonian into it the same year. The bench out front holds eight low stools and a thermos of amazake. The sky begins twenty paces behind the woodpile.

    Inside is a long table, a paraffin lamp on red, and a kettle that stays warm all night. Guests sit in the lamp-light for a fifteen-minute briefing on red-light etiquette and what is up tonight, then we step out.

    • Telescope20-cm Dobsonian on a wooden rocker, hand-built
    • PointerClass-3R green laser kept above head height
    • LightRed-LED headlamp per guest 20-min dark-adaptation before the eyepiece
    • HeatHibikairo hand warmers · wool blankets free in winter
    • DrinkAmazake or hot cocoa included, served on the bench
    • BriefingHand-drawn sky map marked with tonight’s targets

    — Hoshino-san, on the bench

    A guest silhouetted at the eyepiece of a telescope beneath the Milky Way

    Section five · house rules

    What we ask of you, and what we promise back.

    These are not conditions of sale. They are the etiquette that lets eight people and one telescope have a quiet ninety minutes under a real sky.

    Dark-adaptation etiquette

    Your pupils take about twenty minutes to fully open. White light from a phone torch resets that clock for everyone in earshot.

    • Switch to red mode or airplane mode the moment you step out of the cabin.
    • We lend a red headlamp to anyone who forgets.
    • No photography with flash on the bench.
    • Children are welcome; please keep voices low near the eyepiece.
    • Walk slowly between the bench and the scope — the path has a low step.
    Red-light only on the bench

    Weather cancellation policy

    Achi is high and dry, but weather changes. If the day looks like it will be overcast all night, we cancel.

    • We make the call by 17:00 the day before the session.
    • The call goes by email and SMS — please check before you drive up.
    • Cloud-cover forecasts above 80% at session start → we cancel.
    • If we cancel, you receive a 100% refund, no questions, no fees.
    • If you cancel yourself more than 48 hours ahead, full refund; inside 48 hours, 50% unless we can re-fill the seat.
    Full refund if we cancel
    The lights of Achi Village in the valley below, viewed from the hill path up to Hoshimachi-sha
    The walk up from Hirugami Onsen · 15 min on the marked forest path

    Section six · find us

    Three ways up. None of them require a car if you plan ahead.

    The cabin sits above the Hirugami Onsen village, in the folds of the Achi hillside. Last train down the valley is the JR Iida Line; the onsen bus stops running before our late-night session, so plan accordingly.

    • By rail JR Iida Line to Akagi or Ōshika station, then the local onsen bus to Hirugami Onsen-guchi. Allow 90 minutes from Nagoya by limited express.
    • By bus The Hirugami Onsen bus runs roughly hourly from Iida Bus Terminal. The cabin is a 15-minute uphill walk from the bus stop — we’ll send a hand-drawn map.
    • By car Chuo Expressway, Iida IC — 25 minutes up the valley. Free parking at the onsen village below the cabin. Note the 15-minute uphill walk at the end.
    • In winter Studless tyres or chains. The uphill path is salted but can be slick. We’ll lend wool blankets and hot amazake while you defrost.

    Section seven · winter nights

    December to February is when Achi’s sky gets serious.

    The air is at its driest. Orion climbs the south-east with Sirius at his heel. The Milky Way fades to a faint band, but the constellations sharpen into pinpoints.

    Cold cuts the seeing — the air is still, the stars barely twinkle, and the eyepiece stays steady on the lunar craters. This is when Achi earns its reputation among astronomers, and when Hoshino-san extends the late-night session by half an hour for guests who want to stay out.

    What we hand you
    • Two hibikairo hand warmers per guest
    • Heavy wool blanket (the kind ryokan use)
    • Spare pair of wool socks if yours are damp
    • Amazake on the bench, refills included

    Geminids

    The most reliable annual shower. Up to a hundred meteors an hour at peak on the night of 13 December, slow and bright, often with a green or red afterglow.

    The dark of winter

    Astronomical dark arrives by 18:00 and lasts until 05:00 — nearly eleven hours of stable, cold, transparent sky. The longest nights of the year give the longest sessions.

    Spring bonus: hanamomo

    From late April, the peach orchard on the lower slope blooms pink and white. Guests on the spring twilight session often come an hour early to walk the orchard before the sky darkens.

    Snow-laden firs under the winter Milky Way and a fading dusk

    Section eight · booking

    Send us a note. We reply by hand, usually within the day.

    Eight seats is a small number, and the sky changes every night, so we keep bookings close. Tell us which session you want and how many of you; we’ll write back with the bench availability, the weather window, and a payment link.

    This is a demo site brief@yonderwell.com
    Meeting point Hirugami Onsen · Achi Village
    Hours 17:00 – 23:30 nightly
    Book tonight 3 seats · ¥7,500