Major city · Japan
Kosai湖西市
Kosai is a half-day stop for the Arai checkpoint and Honkō-ji temple, not a base. One night if you want boat races or a quiet lake-side evening.
Kosai sits on the shore of Lake Hamana in western Shizuoka, best known for the Arai Sekisho — the only surviving original checkpoint building from the Tokaido highway. The city also holds Honkō-ji temple with a National Important Cultural Property hall. Most travellers pass through on the way to Hamamatsu or beyond; a few hours are enough unless you stay for the boat races.
More
More ways in
Local time, weather, currency, airports
- Weather
- see forecast
- Currency
- JPY
- Best months
- Mar–May, Oct–Nov
- avoid Jul–Aug (hot and humid)
- Airports
- NGO · FSZ
- Nights
- 0–1
Not a trip line yet
Rules in force · 5
- East Asia ↗Every border in East Asia is a full international border, Hong Kong and Macau included: an entry permission for one never covers the next.
- East Asia ↗Ferries between Korea, Japan and China cancel in rough seas and typhoons; keep a flight or a spare day behind every sea leg.
- Japan ↗IC cards (ICOCA/Suica) are topped up with cash at station machines.
- Japan ↗Smoking while walking is banned in most city centres; use designated areas.
- Japan ↗Shinkansen bags 160–250 cm (L+W+H) need a seat reserved with the oversized-baggage area.
Entry rules depend on your passport. Full visa guide
What is in this basic guide9 covered · 4 not yet ▾
In this guide
Not in this guide yet
- Walking areas with bag rules
- Day plans checked against opening hours
- Airport-to-bed timings and the last safe connection
- Field-checked times and prices
Official sites
Emergency numbers for Kosai110 ▾
Tap a number to call from your phone. These are the numbers listed in this guide; a row marked check has not been verified.
EssentialsQuick answers and what things cost
Essentials
Quick answers and what things cost
Quick answers
The questions people ask first about Kosai, one line each. Tap a card for the full answer.
- Cash or card?Cities are increasingly cashless; temples, small restaurants and some lodging taxes still want cash.Japan-wide
- SIM or eSIMData-only eSIMs are the easy route: buy before you fly; voice SIMs need a residence card.Japan-wide
- Tap waterSafe from the tap everywhere; stations and parks have fountains.Japan-wide
- TippingRestaurants and bars: No tip; staff will chase you to return money left on the table.Japan-wide
- Plugs & powerSockets A/B. US/Canada (A/B): fits · UK/Ireland (G): adapter · Australia/NZ (I): adapter. 100 V: UK and AU 230 V-only devices need a converter; most chargers are dual-voltage.Japan-wide
- SafetyKosai is a quiet, safe city.
Show all 12 answers
- RestroomsFree, clean public toilets in stations, parks and konbini; paper goes in the toilet.Japan-wide
- Emergency numbers110 police · 119 fire and ambulance (not 911, 999 or 000)
- Sundays & holidaysMuseums close on Mondays (Tuesday when Monday is a holiday); many family restaurants close one weekday, often Tuesday or Wednesday…Japan-wide
- Your embassyFind your embassy's 24-hour line before you fly.
- AirportcheckNGO Chubu Centrair (About 1 h 15 min by car or bus; check train connections via Hamamatsu).
- Getting aroundJR Tokaido Line connects Kosai Station to Hamamatsu (about 15 min) and Toyohashi.
Cost cheat-sheet
Typical prices for the everyday things, as ranges. Your currency is shown next to the local price.
- Coffee¥300–500 (≈ US$3–4)
- Street or quick mealBeer: draught / can at a konbini¥500–700 (≈ US$4–5)¥250–350 (≈ US$2–3)
- Taxi, about 5 km (3 mi)Taxi, about 3 mi (5 km)5 km (3.1 mi) taxi3.1 mi (5 km) taxi¥2,000–2,500 (≈ US$14–17)
- Museum or sight ticketArai Sekisho entry¥300 (≈ US$3)
- Budget bedHostel or guesthouse bed, a night, per person¥3,500 (≈ US$25)
- Mid-range bedBusiness-hotel double room, a night, per room¥12,000 (≈ US$85)
- High-end bedBusiness-hotel double room, a night, per room¥20,000 (≈ US$140)
A day, not counting the bed: Budget ¥6,000 (≈ US$45) · Mid ¥12,000 (≈ US$85) · High ¥20,000 (≈ US$140)
Local prices, with USD next to them (rates 2026-09 (approximate); change it in the header). Ranges are desk estimates: check locally. Every price and the budget calculator →
DecideWhat it is known for, and when the weather works
Decide
What it is known for, and when the weather works
At a glance
What the city is known for, how you fly in, and where to find the phrases.
- Airports
- NGO Chubu Centrair (About 1 h 15 min by car or bus; check train connections via Hamamatsu) · FSZ Shizuoka Airport (About 1 h 30 min by car; limited public transport)
Best months at a glance
From the guide's best and avoid lists
Jan
not flagged
10°C (50°F)50°F (10°C)
Feb
not flagged
11°C (52°F)52°F (11°C)
Mar
Best
15°C (59°F)59°F (15°C)
Apr
Best
20°C (68°F)68°F (20°C)
May
Best
25°C (77°F)77°F (25°C)
Jun
not flagged
28°C (82°F)82°F (28°C)
Jul
Avoid
32°C (90°F)90°F (32°C)
Aug
Avoid
33°C (91°F)91°F (33°C)
Sep
not flagged
29°C (84°F)84°F (29°C)
Oct
Best
23°C (73°F)73°F (23°C)
Nov
Best
17°C (63°F)63°F (17°C)
Dec
not flagged
12°C (54°F)54°F (12°C)
Best: Mar–May, Oct–Nov. Avoid: Jul–Aug. Month by month →
Warmest Aug (33°C (91°F)91°F (33°C)), coolest Jan (1°C (34°F)34°F (1°C) low), wettest Jun (13 rain days), driest Jan (5). Averages, not a forecast.
Weather and climate
Kosai: next 7 days
Loading forecast…
Forecast: Open-Meteo (CC BY 4.0), model data for this point.
Air quality
Loading…
Model estimate (CAMS via Open-Meteo), not a street-level station; readings near busy roads run higher.
Jan
10°C (50°F)50°F (10°C)
1°C (34°F)34°F (1°C)
5 rd
Feb
11°C (52°F)52°F (11°C)
1°C (34°F)34°F (1°C)
7 rd
Mar
15°C (59°F)59°F (15°C)
4°C (39°F)39°F (4°C)
10 rd
Apr
20°C (68°F)68°F (20°C)
10°C (50°F)50°F (10°C)
10 rd
May
25°C (77°F)77°F (25°C)
15°C (59°F)59°F (15°C)
11 rd
Jun
28°C (82°F)82°F (28°C)
19°C (66°F)66°F (19°C)
13 rd
Jul
32°C (90°F)90°F (32°C)
23°C (73°F)73°F (23°C)
13 rd
Aug
33°C (91°F)91°F (33°C)
24°C (75°F)75°F (24°C)
9 rd
Sep
29°C (84°F)84°F (29°C)
21°C (70°F)70°F (21°C)
12 rd
Oct
23°C (73°F)73°F (23°C)
14°C (57°F)57°F (14°C)
9 rd
Nov
17°C (63°F)63°F (17°C)
8°C (46°F)46°F (8°C)
7 rd
Dec
12°C (54°F)54°F (12°C)
3°C (37°F)37°F (3°C)
6 rd
High / low, both scales · rd = rain days
Arrive & moveAirports are listed under At a glance; this is how to move once you are in
Arrive & move
Airports are listed under At a glance; this is how to move once you are in
Getting around
JR Tokaido Line connects Kosai Station to Hamamatsu (about 15 min) and Toyohashi. Buses are infrequent; a car is best for the lake shore and boat race venue. Taxis are available at the station.
Nearest full guides
Straight-line distance, not travel time
See & doDay-trips, door to door
See & do
Day-trips, door to door
Day-trips
Door to door: About 30 min
JR Tokaido Line from Kosai Station, about 15 min
Hamamatsu Castle, unagi, and the musical instrument museums.
Door to door: About 25 min
JR Tokaido Line, about 10 min
Yamaha headquarters and the Communication Plaza.
Door to door: About 45 min
JR Tokaido Line, about 30 min
Kakegawa Castle and the Kachō-en garden.
Eat & sleepWhich area to sleep in
Eat & sleep
Which area to sleep in
Where to sleep
Areas, not hotels: pick the one that fits your arrival time and plans.
Near JR Kosai Station
Convenient for trains; a few business hotels and minshuku.
Lake Hamana shore
Ryokan and guesthouses with lake views; requires a car or taxi.
PracticalWhat a day costs, what to watch out for, and the pocket card
Practical
What a day costs, what to watch out for, and the pocket card
Cost per day
- Budget
- ¥6,000–9,000 (≈ US$45–65) excl. bed
- Mid
- ¥9,000–15,000 (≈ US$65–110) excl. bed
- High
- ¥15,000 (≈ US$110)+ excl. bed
Trip budget
| Business-hotel double room1 × 1 night × ¥12,000 | ¥12,000 |
| Food, local transport, entries2 × 1 day × ¥12,000 | ¥24,000 |
| JR Tokaido Line Kosai–Hamamatsu return2 × ¥600 · check | ¥1,200 |
| Arai Sekisho entry (adult)2 × ¥300 | ¥600 |
| Honkō-ji entry (adult)2 × ¥300 | ¥600 |
| Buffer 10%Price creep, a taxi you did not plan, one splurge | ¥3,840 |
| Trip total≈ ¥21,120 per person per day, bed included | ¥42,240≈ US$300 |
2026 estimate in yen; flights and rail passes excluded.
Prices of common things
| Coffee | ¥300–500 (≈ US$3–4) |
| Unagi (eel) set meal | ¥2,000–4,000 (≈ US$14–30) |
| Beer: draught / can at a konbini | ¥500–700 (≈ US$4–5) / ¥250–350 (≈ US$2–3) |
| 5 km taxi | ¥2,000–2,500 (≈ US$14–17) |
| JR Kosai–Hamamatsu one way | ¥300 (≈ US$3) (check) |
| Arai Sekisho entry | ¥300 (≈ US$3) |
| Honkō-ji entry | ¥300 (≈ US$3) |
2026 estimate; check locally.
Watch out
Safety
- Arai Sekisho closes at 16:30; arrive by 15:00 to see both the checkpoint and archives.Arai Sekisho closes at 4:30 PM; arrive by 3:00 PM to see both the checkpoint and archives.
- Boat races have their own schedule; check the official site before going.
- English signage is limited outside the checkpoint and temple.
Emergency numbers
- Police
- 110
- Fire and ambulance
- 119
Pocket card
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Kosai湖西市
Pocket card · Voykit
My bed tonight
—
—
—
ここまでお願いしますTo this address, please
Emergency
- Police110
- Fire and ambulance119
Embassy
The nearest consulate is in Nagoya (US) or Osaka (most others). Embassies are in Tokyo.
My embassy: —
Fare anchors (2026 estimate)
- Kosai Station → Arai Sekisho: about ¥1,500–2,000 (≈ US$11–14) by taxi, 10 min (check)
- Kosai Station → Hamamatsu Station: about ¥300 (≈ US$3) by JR, 15 min (check)
Say or show
- すみません — Excuse me / Sorry (sumimasen)
- ありがとうございます — Thank you (arigatō gozaimasu)
- いくらですか？ — How much is it? (ikura desu ka)
- 関所はどこですか？ — Where is the checkpoint? (sekisho wa doko desu ka)
- カードで払えますか？ — Can I pay by card? (kādo de haraemasu ka)
- トイレはどこですか？ — Where is the toilet? (toire wa doko desu ka)
Deep diveWhat this guide covers so far, and its sources
Deep dive
What this guide covers so far, and its sources
Not a trip line yet
This is a basic guide: no airport-to-bed contract, walking clusters or day plans are published for Kosai. Airport, fare and schedule details are unverified; check the operators before you fly.
What we know, and what is coming
On this page
- Best months: Mar–May, Oct–Nov · avoid Jul–Aug (hot and humid) · month by month →
- 2 airports and 2 areas to sleep in
- Weather: a 7-day forecast and monthly averages
- Cost per day in 3 bands
- 3 day-trips, door to door
- 3 things to watch out for, with emergency numbers
Coming as the guide grows
- Place pages for Arai Sekisho, Honkō-ji and the boat race venue with verified hours and prices.
- Eat pages for unagi and local seafood around Lake Hamana.
- Sleep pages for ryokan on the lake shore.
Sources
Ask about Kosai
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