Type 98 320 mm mortar
Type 98 320 mm mortar is a mortar or artillery model.
Also recorded as 320 mm Type 98 mortar.
Overview
Type of spigot mortar.
In detail
It is associated with Japan.
Sources
Each source is named with the standing the house places on it, so the evidence can be weighed rather than taken on trust.
reference work · Reputable secondary · Wikipedia
“Type 98 320 mm mortar”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q3297746: Type 98 320 mm mortar
Consult the source