The Nio gate to Jyoso-ji is some distance from the temple itself, though the temple complex was much larger in earlier times. It is said that the temple was founded by Gyoki, which would make it early 8th Century.
It is also said that Gyoki carved the Nio, and while they are fairly old I am certain that is a rather fanciful legend.
Located in the mountains behind Sada Shrine, the temple was the Okunoin (inner sanctuary) of that shrine. It now belongs to the Shingon sect.
In front of the main hall is a 450 year old plum tree, but it had long since past its blooming when I visited in June.
The main hall has some fine dragon carvings above the entrance.