Odawara · Hayakawa hillsNo.100★Open in map →
Ishigakiyama Ichiya Castle
A hilltop park in Odawara built around the stone-wall ruins of the fortress the warlord Toyotomi Hideyoshi raised as his 1590 command post — the first fully stone-clad castle in the Kanto region, set among mandarin-orange groves with Sagami Bay below.
In 1590 Toyotomi Hideyoshi laid siege to Odawara Castle, the stronghold of the Late Hojo clan, and built his own stone-walled castle on the ridge across the Hayakawa valley as his headquarters. Records describe it as the first fully stone-clad castle in the Kanto region, its walls stacked in the rough nozura-zumi style — undressed field stones without mortar — by the Ano, a guild of stonemasons from Omi province near Lake Biwa. The famous 'one-night castle' name comes from the reveal, not the build time: the castle was constructed behind a screen of trees, which were then cut down in a single night, so the defenders of Odawara Castle woke to find a fortress that seemed to have appeared overnight. Today the ridge is Ishigakiyama Ichiya Castle Historic Park, where the stone walls, terraced enclosures, and the keep platform survive among mikan groves.
Why it stays quiet
Almost everyone visits the rebuilt Odawara Castle down in the town, and few make the ~50-minute climb up from Hayakawa to these ruins. There is no station at the site, the sightseeing bus runs only on weekends and holidays, and there is little English signage, so on ordinary days the park stays quiet.
Background & history
The castle was raised at the peak of Hideyoshi's Odawara campaign — the push that forced the Late Hojo clan to surrender and completed the unification of Japan. Documented accounts say the work drew around 40,000 laborers and took roughly 80 days, from about the fourth to the sixth month of 1590. The ruins were later designated a National Historic Site, and the grounds, about 5.8 hectares, were opened as a free park.
What to look for — in walking order
- Farm road approach
- the ~50-min uphill walk from Hayakawa Station through citrus groves to the park entrance
- Nozura-zumi stone walls
- ramparts of rough, undressed stones stacked by the Ano masons, still standing after 430 years
- Keep platform and enclosures
- the tenshu platform and terraced kuruwa that mark the castle's layout
- Observation deck
- wide views over Odawara town and Sagami Bay; Tokyo Skytree visible on clear days
How to enjoy it
Walk the loop through the terraced enclosures to the keep platform and observation deck — clear days open the view over the bay and the old castle town below. In autumn the mikan groves around the ruins come into season. The site pairs naturally with Odawara Castle across the valley.
How to actually get there
- Tokyo Stn → Odawara Stn (JR Tokaido Line ~80-90 min, or Shinkansen ~35 min).
- Odawara Stn → Hayakawa Stn (JR Tokaido Line, 1 stop, ~3 min).
- Hayakawa Stn → the park (walk uphill on the farm road, ~50 min).
- Weekend option: Odawara Stn East Exit → the park (Umemaru sightseeing bus, ~15 min).
- Tokaido Line + walk (or weekend bus)
- Tokyo Stn →(JR Tokaido Line, ~80-90 min; or Tokaido Shinkansen ~35 min)→ Odawara Stn →(JR Tokaido Line, 1 stop, ~3 min)→ Hayakawa Stn → walk uphill on the farm road ~50 min to the park. On weekends and holidays you can instead take the Umemaru sightseeing bus from Odawara Station East Exit (~15 min to the park). No regular bus runs on weekdays — on a weekday you walk from Hayakawa.
- Return by train (or weekend bus)
- Walk back down to Hayakawa Station for frequent Tokaido-Line trains; on foot there is no last-bus to worry about. If you took the weekend Umemaru bus up, it runs only until mid-afternoon (last runs around 15:45) — check the day's timetable at the Odawara stop before you set out.
Before you go
- Cash
- The park itself is free. A well-known bakery-cafe on site takes cash — useful at the top. Rural areas here can be cash-first, so carry some coins.
- Closing days
- The old stone walls can be loose, and the grounds have steps and uneven ground (not wheelchair-accessible). Stay on the paths and do not climb on the ramparts. There is no staffed office on site.
- Another way
- On weekends and holidays only, the Umemaru sightseeing loop bus reaches the park from Odawara Station East Exit (bus stop 1); on weekdays there is no bus and you walk from Hayakawa.
- After you get off
- From Hayakawa Station, follow the paved farm road uphill through the citrus groves, about 50 minutes to the park entrance.