Kato Unijoiner Tool
More than just to pull the Unijoiners...
Here in the US, it well known that the Unijoiner tool is used to remove the Unijoiners from the Kato track. But, that odd shape of the tool is by design. The tool is also:
height gauge - Check the clearance over the track such as bridges or tunnels
track gauge - Check the spacing between the two tracks
clearance gauge - Check that there is enough room on the left and right of the track
loading/platform height gauge - Check that the height of the loading dock (or passenger platforms) are at the correct height
The Kato Unijoiner tool dimensions compared to the NMRA Standards Gauge. (both N-Scale)
You can see how many of the dimensions are the same, or very close.
After doing the measuring/comparing, I asked about the tool on one of the Japanese Facebook pages, and I eventually got back some official confirmation. Two pictures from an official Kato "track book" (Not positive of the English name of this book, but my understanding is it says "Let's Enjoy Driving! N-scale Model Train" and then in the red box it says Unitrack Guidebook )
Hobby Search listing of the book: https://www.1999.co.jp/eng/10075133
Inside the book, there are two photos showing how the Unijoiner tool can be used besides just pulling the joiner.
I am not suggesting they are the best 'replacement' to the NMRA official standards gauge for US modelers, particularly since the Kato tool would be using Japanese standards (so the scaling could be off a touch). But if you are just starting out, or you don't have your NMRA gauge handy, this Kato tool can be used.
The NMRA store, n-gauge clearance tool: https://www.nmra.org/store/products/n-scale-clearance-n-gauge