One thing first. You cannot go inside the Hirotsu House. The interior is closed to protect the building, and visitors see the exterior and the garden only. Planning an itinerary around the tatami rooms or the upper floor is how people end up turning back at the gate.
So what is there to see
What you see is the outside of the building and the grounds. Latticed wooden windows, low tiled eaves, and a garden running along a stone boundary are all visible at once. The stone lantern at the centre of the yard, the low stepping stones and the shaped pines are within the viewing area. Watch your footing around the garden stones, and follow the on-site guidance on photography and equipment.
When to go
Opening hours are Tuesday to Sunday, 10:00 to 17:00, and it is closed on Mondays. Admission is free. If your Gunsan day falls on a Monday, treat this stop as unavailable rather than hoping to see it from the street.
What the building is
It stands at 58-2 Sinheung-dong and dates from 1925, built by a Japanese textile merchant as a two-storey wooden house. It is designated National Registered Cultural Heritage No. 183 and retains the characteristics of shoin-zukuri, a traditional Japanese residential style. Gunsan was a port at the centre of rice and goods extraction through the colonial period after it opened in 1899, which concentrated Japanese-built architecture in the city, and because post-liberation development largely passed the area by, Sinheung-dong survives close to its original form.
What is within walking distance
The density around it makes turning back after one building a waste. Dongguksa Temple is a five-minute walk, the Modern History Museum ten minutes, the former Bank of Joseon Gunsan Branch two minutes, and the former Japanese 18th Bank Gunsan Branch one minute from that. Dongguksa, founded in 1909, is the only Japanese-style Buddhist temple remaining in Korea, and its grounds hold a memorial stele to victims of forced mobilisation.
Travel time and viewing time are not the same thing, though. Seeing all five means allowing half a day rather than an hour. The half-day route covering the modern history street as a whole is written up separately, so read that alongside this if you are planning the full circuit.
Timings for each stop, photo points and parking information are in the Gunsan Japanese house guide on the WeBring blog.