Unless I've forgotten something huge, Japan doesn't have Manchuria. They may even have lost bits of Korea in losing their war with Russia--remember, the one that motivated them to support some insurgent black ops in Poland, the ones Wilhelm thought would be a neat bit of derring-do to help the Japanese with.
The one that was Russia's reason for starting this latest big war.
I kept waiting for the Japanese to pile on as Russia began going down for the count. I guess they were too messed up by the last war to be ready for a rematch, even with Russia already on the ropes.
On paper anyway, Manchuria isn't carved out of Russia, it is taken from China, so while this time frame may have been a less costly time for Japan to take it, it would mean starting a new war, and while China had no true friends, there were a lot of great powers circling around who had interests there, so for Japan to move on Manchuria would be a real case of rocking the boat. Russia would have been one of the powers wanting to deter such a move on Japan's part, but other European powers, and even at this early date the USA, would not approve either.
Now I worry I did forget something, either a curious turn of the old Russo-Japanese war or Japan launching some adventure or other. But I still don't think they'd be allowed to just claim Manchuria!
Now, given that Japan is per OTL anyway a British ally at this point, and that the Germans have very cordial relations too, and Germany and Britain have decently good relations with each other, I could see the Japanese being given carte blanche as far as they are concerned to start treating Manchuria like a protectorate--to have lots of exploitive investments there, and interfere with the nominal government, enjoy extraterritorial privileges there, and so on...so it might (if we ever get confirmation of those things happening there that is) have it cross-hatched in both Japanese and Chinese colors. But not a formal addition to the Japanese Empire, not yet!
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Thought it might be prudent to read up a bit on Manchuria OTL before posting this; here are some relevant bits from Wikipedia (
History of Manchuria)
To the north, the boundary with Russian Siberia was fixed by the Treaty of Nerchinsk (1689) as running along the watershed of the Stanovoy Mountains. South of the Stanovoy Mountains, the basin of the Amur and its tributaries belonged to the Qing Empire. North of the Stanovoy Mountains, the Uda Valley and Siberia belonged to the Russian Empire. In 1858, a weakening Qing Empire was forced to cede Manchuria north of the Amur to Russia under the Treaty of Aigun; however, Qing subjects were allowed to continue to reside, under the Qing authority, in a small region on the now-Russian side of the river, known as the Sixty-Four Villages East of the River.
In 1860, at the Convention of Peking, the Russians managed to acquire a further large slice of Manchuria, east of the Ussuri River. As a result, Manchuria was divided into a Russian half known as "Outer Manchuria", and a remaining Chinese half known as "Inner Manchuria". In modern literature, "Manchuria" usually refers to Inner (Chinese) Manchuria. (cf. Inner and Outer Mongolia). As a result of the Treaties of Aigun and Peking, China lost access to the Sea of Japan. The Qing government began to actively encourage Han Chinese citizens to move into Manchuria since then.
The Manza War in 1868 was the first attempt by Russia to expel Chinese from territory it controlled. Hostilities broke out around Vladivostok when the Russians tried to shut off gold mining operations and expel Chinese workers there...Inner Manchuria also came under strong Russian influence with the building of the Chinese Eastern Railway through Harbin to Vladivostok. Some poor Korean farmers moved there. In Chuang Guandong many Han farmers, mostly from Shandong peninsula moved there, attracted by cheap farmland that was ideal for growing soybeans.
During the Boxer Rebellion in 1899–1900, Russian soldiers killed ten-thousand Chinese (Manchu, Han Chinese and Daur people) living in Blagoveshchensk and Sixty-Four Villages East of the River.[25][26] In revenge, the Chinese Honghuzi conducted guerilla warfare against the Russian occupation of Manchuria and sided with Japan against Russia during the Russo-Japanese War.
{my bolding. Note that we are into butterflied times by this point, but my point would be that there would be little reason to expect Japan to get formal claims on the territory recognized--especially because ITTL they don't win.
But they do have some leverage with the regional native and recent Han immigrants it would seem!}
From 1911 to 1931 Manchuria was nominally part of the Republic of China. In practice it was controlled by Japan, which worked through local warlords.
And so that was pretty much my guess as to the nature of Japanese power in Manchuria--no formal power, but lots of influence. ITTL their defeat would put them on the back foot, but perhaps make them all the more sympathetic and attractive to their fellow East Asians who also suffer at Russian hands.
I am nagged by the vague memory of some discussion by carlton_bach of schemes in the Far East against Russia, but IIRC they are either actions of British-coordinated Central Asians or the deeds of units affiliated with the official Chinese government, which at this point ITTL as well as OTL, is still the Qing Dynasty. OTL that dynasty would be overthrown in a matter of years leading to a nominal Chinese Republic, but of course that Republic had very little central control and China was actually parceled out among local warlords--or regions under foreign influence.
As long as the dynasty holds, however weakly and nominally, it would be embarrassing to powers like Britain to recognize a formal Japanese sphere of influence in Manchuria.
But while I do think you should strike it from the map as a full-on possession of Japan, it looks more and more like there would indeed be a predominant degree of Japanese
influence there.
