Here are pictures of my Jonnaught and a very similar one that I do not own marked Kanamaru. The Jonnaught is straight gripped with double triggers.
The last picture is the Mashiro that is now put back together. It just needed new springs when I got it. It has a round knob grip and double triggers.
There was a Japanese version of a Greener on Gunbroker last week. It went for less than $300, but the stock and forend were damaged and the forend latch was corroded on the edges.