In the old days Kings/Emperors/heads of states did NOT visit other countries, except for conquest or submission.
In Asia, there was a strong taboo of Kings/Emperors NOT visiting other countries.
On 299 BC, King Huai of Chu visited the capital of Qin , the strongest state at that time, for a summit . The King of Qin arrested Huai for some trumped up charge, and Huai never returned to Chu and died in Qin. While Huai was in Qin which created an anarchy at Chu, Qin installed a pro-Qin figure as the next monarch, and Chu never recovered.
That lesson was never forgotten, and Kings/Emperors who ruled China only went to foreign countries as a conqueror, not for any reason. States recognizing the superiority of the Chinese Emperor had to send envoys to the Chinese Capital; but the kings of such states, except in some rare cases, didn't go to the Chinese capital either since going to there and personally showing respect to the Chinese Emperor would undermine their authorities back home.
Korea had a such king, King Chungsun (reigned 1308-1313). He was a grandson(through his mother) of Kublai Khan of Mongolia, who also founded the Yuan dynasty of China, and so Chungsun was more interested upon what was happening in the Yuan capital than Korea.
The KDrama "The King in Love" is about King Chungsun, played by Lim Siwan.
Chungsun spent virtually all of his 5 year reign at the Yuan capital, meddled with the Imperial succession of the Yuan and was an important figure in the Yuan court (he eventually abdicated because the Korean officials urged him too often to return and he didn't want to lose his support in the Yuan capital), but neglected Korea so Korean literati used him as an example to warn further monarchs not to leave Korea to visit other countries.
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The very title of IU's concert is "The Golden Hour - Under the Orange Sun".
The reference to the Orange Sun is a reference to the IU-Suga song "Eight".
Until June 14, it would have been impossible to imagine that such duet would ever be possible in 10 years since BTS would be having a world tour and Suga showing up in IU's concert would have been nothing less than a shock.
BTS had conquered the entire world, with no act over it anywhere on the entire world, while Lee Jieun never sold any arena, let alone a stadium, With their vastly different international stature, such meeting was inconceivable.
At most such meeting would have been possible if IU were willing to show herself up to a BTS concert, but she only showed up in concerts held by those she personally knew.
The risk was too big. One side going to the other side was kinda of too risky since their pride, stature and positions would not allow it.
Then June 15, 2022 occurred.
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I see J Hope appearing in IU's show as a capitulation.
Now, it is very possible that what seemed to begin as an innocent collaboration is turning into a trap which brings down an Empire.
This is forgivable since Psy had made a mark around the world.
But, Suga showing up in an event, which would probably have not taken place if the event of June 15 did not occur, to collaborate with BTS' most dogged, most persistent and most determined opponent is something for which I don't have words to describe.
"
So are you happy now (happy now)
Finally happy now yeah (yeah)"
If the event hinted at the description of The Golden Hour, "Under the Orange Sun", does occur I know I won't be happy now.