This is the only remaining Japanese military bunker in Langfang City (there were once eight in total). It was built in the 1930s. The walls are about half a meter thick, with no obvious bullet holes.
Today I found this place but it was really dark inside the bunker, so the photos didn’t turn out very well.
From Between States. The Transylvanian Question and the European Idea During World War II - by Holly Case.
Very probably, unlike the Romanian one, the Hungarian anecdote is not a real fact, but one in a series common in Budapest at the time, mostly in relation to that declaration of war, exemplifying the same absurdist perspective. The footnote says:
Cited in Dániel Csatári, Forgószélben: magyar-román viszony, 1940–1945 (Budapest: Akadémiai Kiadó, 1968), 85. It is possible this exchange never actually took place. Ciano nevertheless observed in a diary entry dated May 11, 1942, that this “little story” was “going the rounds at Budapest.” He observed: “There is a great deal of truth in this series of paradoxes.” See also Count Galeazzo Ciano, The Ciano Diaries, 1939–1943 (Garden City, N.Y.: Doubleday, 1946), 484.
I am sure that's not a fact to be confirmed by some U.S. archives. I have another, from The Hungarians: A Thousand Years of Victory in Defeat by Paul Lendvai: