At the moment, almost all ships in the War Thunder navy fly a flag on their stern.
However, in the Imperial Japanese Navy, for example, the battle flag is flown on the mainmast during combat, and together with the lowering of the aft flag (which is moved to the aft mast gaff), there are at least two flags (there are also signal flags and flag indicating the rank of the commander, but this is not discussed at the moment).
This is based on the Navy Flag Decree, which was revised in 1932 and states in Article 28: ‘The flag of warships shall be flown on the rear flagpole (where it is currently flown in the warthunder) or diagonal girders of ships and special service vessels.
Article 30: When a ship is preparing to engage in battle, the warship’s flag should always be hoisted without regard to the provisions of the preceding article (Article 29: Provisions on the time for hoisting the flag while the ship is at anchor).
During ship combat, in addition to those stipulated in the preceding paragraph, one warship flag shall be flown at the top of the outer mast. The following is a summary of the provisions of this article.
What this means is that IJN vessels will need to hoist another flag (on the top of the main mast).
However, in Article 15 of the Maritime Self-Defence Force Flag Regulations (Maritime Self-Defence Force Instruction No. 44), enacted in 1955, for vessels belonging to the Maritime Self-Defence Force, it is stated that ‘(in the case of the use of force, etc.)
'Article 15-2: When a ship of the Self-Defence Forces ordered to deploy pursuant to the provisions of Article 76, paragraph 1 of the Law, uses armed force, the flag of the Self-Defence Forces shall be flown on the main mast.’
The correct answer seems to be the one on the mainmast because it says.
I hope that this flag issue will be brought into line with the facts, while also listening to the examples of other national navies in order to make warthunder a game that is as realistic as possible.