One of the most disturbing theories surrounding Four Hands has emerged after Jeong-yo’s disappearance and unexpected return.
Did Kang Seung-woon deliberately remove Jeong-yo from Bi-o’s path so that his own grandson could eventually become No. 1?
At first, the theory sounds possible.
Jeong-yo was the natural genius standing directly in Bi-o’s way.
Then Jeong-yo disappeared.
His right arm was seriously injured.
His career as a pianist was effectively destroyed.
And years later, he returns not as Bi-o’s rival at the piano, but as a conductor.
From Bi-o’s perspective, the greatest obstacle in front of him simply vanished.
But there is a major problem with this theory.
Kang Seung-woon had already shown that he was willing to choose Jeong-yo over his own grandson.
So why would a man who refused to favor Bi-o suddenly destroy Jeong-yo in order to help Bi-o win?
That contradiction may be one of the biggest clues in Four Hands.
Why Viewers Suspect Kang Seung-woon
The suspicion begins with one simple fact.
Jeong-yo was dangerous to Bi-o.
Not physically.
Musically.
Bi-o had spent years training to become an elite pianist. He possessed technique, discipline and ambition.
But Jeong-yo had something Bi-o could not easily acquire through practice.
Natural musical instinct.
Jeong-yo could interpret music differently. He seemed able to understand and express things that Bi-o had spent years trying to perfect.
And Kang Seung-woon noticed it.
That recognition was devastating for Bi-o because Seung-woon was not simply a famous conductor.
He was Bi-o’s grandfather.
Bi-o did not only want to defeat Jeong-yo.
He wanted his grandfather to look at him the way he looked at Jeong-yo.
That makes Jeong-yo more than a rival.
He becomes the person standing between Bi-o and the recognition he has wanted for years.
Then Jeong-yo Suddenly Disappears
This is where the theory becomes uncomfortable.
The young genius who threatens Bi-o’s position disappears from the piano world.
Later, we learn that Jeong-yo’s right arm was seriously injured.
The injury is severe enough to change the direction of his musical life.
The pianist who could have competed with Bi-o can no longer follow the same path.
From the outside, the result appears brutally convenient.
Bi-o’s greatest rival is gone.
That naturally raises suspicion.
Was Jeong-yo’s disappearance simply a tragedy?
Or did someone benefit from removing him?
And if someone did, viewers inevitably have to look at the adults who had power over both young musicians.
Kang Seung-woon is therefore impossible to ignore.
But Seung-woon’s Earlier Choice Creates a Major Contradiction
There is one piece of evidence that strongly challenges the theory.
When Seung-woon had the opportunity to favor his grandson, he did not simply do so.
He recognized Jeong-yo’s talent.
More importantly, he was willing to choose Jeong-yo for an important musical opportunity even though he knew how badly Bi-o wanted his recognition.
That matters enormously.
If Seung-woon’s ultimate goal was always to make Bi-o No. 1, the easiest solution would have been obvious.
Choose Bi-o from the beginning.
He was his grandson.
Nobody would have been surprised if a grandfather supported his own family.
Instead, Seung-woon made the more painful choice.
He chose the musician he believed deserved the opportunity.
And Bi-o was hurt by it.
That does not look like the behavior of a man willing to manipulate everything to guarantee his grandson’s victory.
In fact, it suggests almost the opposite.
Seung-woon may value musical judgment more than Bi-o’s feelings.
Was Choosing Jeong-yo Actually the Fair Decision?
This is an important point because Seung-woon can easily appear cruel from Bi-o’s perspective.
Bi-o worked relentlessly.
He desperately wanted his grandfather’s approval.
Then another young pianist appeared and received the recognition Bi-o believed he had earned.
Emotionally, it is easy to sympathize with Bi-o.
But fairness is a different question.
If Seung-woon genuinely believed Jeong-yo was the better choice, selecting Bi-o simply because he was his grandson would itself have been unfair.
A respected conductor cannot claim to judge musicians honestly while secretly giving important opportunities to family members.
So perhaps Seung-woon’s original mistake was not choosing Jeong-yo.
Perhaps his mistake came afterward.
Seung-woon May Have Underestimated Bi-o’s Wound
This may be the more convincing criticism of the grandfather.
Seung-woon appears to understand music exceptionally well.
But understanding music and understanding a wounded young man are not necessarily the same thing.
Bi-o did not experience Jeong-yo’s selection as an ordinary professional defeat.
To him, it was personal.
The person making the decision was his grandfather.
And the person being chosen was the rival who possessed the natural gift Bi-o feared he could never match.
That combination could destroy a young musician’s self-worth.
Seung-woon seems to recognize the danger of Bi-o’s obsession with Jeong-yo.
His warning about their relationship is especially significant.
He essentially tells Bi-o to think about who will become completely devastated if this rivalry continues.
That sounds less like a grandfather secretly preparing Bi-o’s victory and more like a man who already sees Bi-o destroying himself.
Then What Did Seung-woon Mean by That Warning?
This could become one of the most important lines in the entire drama.
There are at least two ways to interpret it.
The first is psychological.
Seung-woon understands that Jeong-yo is naturally gifted and fears that Bi-o’s obsession with defeating him will eventually destroy Bi-o emotionally.
In that interpretation, the person who will become “completely wrecked” is Bi-o.
But there is another, darker interpretation.
What if Seung-woon already knew that the rivalry between the two boys would eventually lead to something much worse?
If later episodes reveal that he knew more about Jeong-yo’s disappearance or injury than viewers currently realize, the meaning of that warning could change completely.
It could become foreshadowing.
For now, however, the drama has not provided enough evidence to make that conclusion.
Could Seung-woon Have Removed Jeong-yo Without Causing His Injury?
There is also a middle possibility.
The theory does not have to be all or nothing.
Perhaps Seung-woon did interfere with Jeong-yo’s career.
That does not necessarily mean he caused—or wanted—Jeong-yo’s physical injury.
He might have separated the two young pianists.
He might have cancelled an opportunity.
He might have believed distance was necessary because their rivalry had become destructive.
If something later happened to Jeong-yo after that decision, Seung-woon could still carry guilt without being directly responsible for the injury.
This would fit the drama much better than turning him suddenly into a simple villain.
Four Hands has repeatedly presented choices that can be reasonable from one perspective and devastating from another.
Seung-woon could have made a decision he believed would protect the boys—
only for that decision to contribute indirectly to a tragedy.
And What About Yoon Seon-joo?
This is where Seung-woon’s wife, Chairwoman Yoon Seon-joo, becomes extremely important.
A growing viewer theory suggests that Seon-joo may have helped Jeong-yo after his piano career collapsed and possibly supported his transition into conducting.
If that theory is eventually confirmed, it creates a fascinating possibility.
What if Seung-woon pushed Jeong-yo away, while Seon-joo helped him rebuild?
The husband and wife would then represent two completely different responses to the same tragedy.
Seung-woon might believe separation was necessary.
Seon-joo might believe Jeong-yo should not lose his entire future because of what happened.
Her departure from the household would then become much more meaningful.
It could reflect not only a marital conflict but also a fundamental disagreement over how Jeong-yo was treated.
Again, this remains speculation.
But Jeong-yo’s return as a conductor makes Seon-joo’s role worth watching very closely.
The Biggest Problem With the “Grandfather Did It for Bi-o” Theory
There is still one question the theory cannot easily answer.
Why would Seung-woon hurt Jeong-yo for Bi-o after already choosing Jeong-yo over Bi-o?
That is the central contradiction.
If he wanted his grandson to win at any cost, his earlier behavior makes very little sense.
He could simply have favored Bi-o.
Instead, he gave Jeong-yo recognition even though it wounded his grandson.
For that reason, the simplest version of the theory—
“Grandfather got rid of Jeong-yo so Bi-o could become No. 1”—
currently feels too easy.
The truth is likely more complicated.
Seung-woon may have made a decision involving Jeong-yo.
He may know something about his disappearance.
He may even feel responsible for what eventually happened.
But responsibility is not the same as deliberately destroying Jeong-yo for Bi-o’s benefit.
That distinction could become crucial.
Bi-o May Eventually Ask the Same Question
Even if the theory turns out to be false, it could still matter enormously to Bi-o.
Imagine discovering that your greatest rival disappeared after the adults around you interfered.
Then imagine learning that the rival suffered an injury that ended his piano career.
Bi-o may eventually wonder:
Did Jeong-yo disappear because of me?
That question could be far more destructive than losing a competition.
Bi-o wanted to defeat Jeong-yo.
But he wanted to defeat him at the piano.
He wanted to prove that his years of discipline could overcome Jeong-yo’s natural genius.
If Jeong-yo was removed from the competition by injury, manipulation or an adult decision, Bi-o never received the victory he actually wanted.
He was simply left alone.
And that could explain why Jeong-yo’s return as a conductor may shake Bi-o more deeply than another piano competition ever could.
Jeong-yo’s Return Could Force the Truth Into the Open
For years, the missing period in Jeong-yo’s life has allowed everyone to live with their own version of what happened.
That becomes impossible once he returns.
Jeong-yo is no longer merely a memory.
He is standing in front of them again.
And this time, he is holding a conductor’s baton instead of sitting at a piano.
His presence alone could force the adults to confront the decisions they made.
What did Seung-woon do?
What did Seon-joo know?
What happened to Jeong-yo’s right arm?
Why did he disappear?
And most importantly:
Who benefited from his disappearance—and who tried to help him afterward?
Those questions may eventually reveal that the rivalry between Bi-o and Jeong-yo was never only about two young pianists.
The adults around them may have shaped the competition far more than either boy understood.
Final Verdict: Did Seung-woon Remove Jeong-yo So Bi-o Could Win?
At this point, there is not enough evidence to say yes.
The theory is understandable.
Jeong-yo threatened Bi-o’s position, disappeared, suffered a devastating injury and left the piano world.
Bi-o remained.
That sequence naturally creates suspicion.
But Seung-woon’s earlier actions work against the simplest version of the theory.
He had already demonstrated that he was willing to choose Jeong-yo over his own grandson.
That makes it difficult to believe that his only motivation later would suddenly become making Bi-o No. 1.
A more convincing possibility is that Seung-woon made a decision involving Jeong-yo that he believed was justified—but that decision had consequences he never intended.
If so, the real mystery is not whether Seung-woon was secretly a villain.
It is whether an adult who believed he was making the right decision helped create a tragedy.
And that would fit Four Hands far better.
Because the drama’s most interesting question has never simply been:
Who is the better pianist?
It is:
What happens when adults turn two gifted young musicians into rivals—and realize the damage only after it is too late?