I have a feeling this is old news and has been mentioned on this forum already, but I can't find it and I don't see this gun listed on Landships II either. My apologies offered if necessary.
Pit Road appear to have a few different versions of a 1/72 IJA 28cm Howitzer. It seems to come with 4 crew figures, or perhaps 4 figures would be more accurate.
The image is from Hobby Link Japan, and the kits are available from there too.
It was here - http://landships.activeboard.com/t42217741/japanese-tsarist-28-cm-gun-kit-in-172/
Pit-Road do the gun in two scales - 1/72 and 1/35 - and with different permutations of figures and either assembled or unassembled and with optional brass etched parts - they come and go out of production as will be clear from hlj.com (click to include the discontinued entres). (Theuy originally did a white metal kit, or kits, too. But now replaced by plastic.)
I have the 1/35 gun. Cannot comment on accuracy as I had no plans. The parts need a little clean up and filling where there are shrinkage pits, but nothing too bad. Also a little plastic strip to repair the gaps in the rifling (don't use the provided cylinder to assemble the bore around and you can get a clear view from breech to muzzle ...). I also assume that the threads on the breech block screw need to be interrupted but could not find a clear picture and simply went by common sense.
The string for the crane is silly and I replaced it - also cut off the crane head and pivoted it, and modified the shell sling a little.
Anyway I am very pleased with the result when painted in railway engine black, and bare metal for the recoil slides, with grease slathered on them in the form of thick acrylic varnish mixed with Tamiya clear green, orange and smoke.