Yamaguchi House was built in 1615 right after the siege of Osaka. It is one of few merchant houses that remains from early Edo period. The first constructions that Doma, Agaridoma and three rooms are registered as the national important cultural asset. Especially, room of Doma has great crossbeams. Rest of the houses were mostly constructed in 1770's. The unique feature of Sakai merchant house is the tea room. Unlike others, most of Sakai's houses had tea room.

The garden of this house is "Karesansui" style. It's a no water style designed with rock and sand. There are Hazenoki trees that are similar phenomenon of Koyo in Autumn. In Sakai, because of its warm weather, they don't have Koyo in Autumn. So, most people plant Hazenoki for imitating Koyo.