The 105mm Type 5 anti tank gun was an experimental cannon ment to be used on the Ho-Ri tank destroyer. It achived an higher velocity than any other Japanese gun at the time. It also featured an semi autoloader.

There was a high demand in anti tank weapons due the realisation that the small 37mm and the 47mm most commonly used on Japanese tanks was not strong enough to fight the Sherman tanks of the allied forces. Which then led to the creation of the 105mm Type 5 cannon somewhere in 1945. But due to the war ending the project was cut and only a singular complete prototype was made.

You can see the mantlet is very similar to the one on the Ho-Ri