Because Yamato joining the team would ruin the monster trio

This post contains spoilers for One Piece.

Key points

• Yamato's mastery of the Conqueror's advanced Haki and Devil Fruit skill has made her a powerful fighter in Wano.
• Keeping Yamato out of the Straw Hats maintained the balance and dynamic of the trio of monsters.
• With his unique abilities, Yamato's potential entry into the crew could significantly shift the hierarchy of power.

The Wano Country story arc included the debut of many incredible fighters and One piece fans were extremely excited to see them in action. Among the many individuals, Yamato was undoubtedly the most exciting. She was Kaido's daughter but had a soft spot for Kozuki Oden. She was mesmerized after reading Oden's diary. In fact, he began calling himself Oden and openly opposed his father's sadistic ways.

Yamato met Ace many years before the current timeline. During their meeting, Ace told her about Luffy and his dream. Yamato immediately remembered that Roger had also used the same words he had read in Oden's manuscript. He then waited for Luffy to arrive. Yamato finally meets Luffy when the Straw Hat Pirates head towards Wano.

After seeing this, he expresses a desire to join the Straw Hats, and Luffy doesn't seem to mind. So most fans expected Yamato to become a Straw Hat by the end of the arc. After Kaido's defeat, Yamato seemed to have changed his mind and decided to stay behind. His decision left fans perplexed, but in the end it was the right choice because if Yamato had joined, it would have ruined the dynamic of the trio of monsters.

Yamato was a powerful Oni princess

For this conjecture to make sense, fans must remember Yamato's strength. She was exposed to battles and bloodshed at an early age, which made her resolute both physically and mentally. Yamato is capable of using all three types of Haki, which is an impressive feat in itself. But what makes her truly special is her use of the Conqueror's advanced Haki. Until the Wano Country story arc, fans had no idea that Conqueror's Haki could be infused with attacks.

My name is Yamato. I am Kaido's son.

Over time, it has become quite clear that the Conqueror's advanced Haki dramatically increases the damage dealt. Almost all great fighters in One Piece can use Conqueror's Haki in combat. So, the fact that Yamato has access to such a destructive ability puts her in an elite bracket.

Yamato had mastered his devil fruit

In addition to having such powerful Haki, Yamato is also a Devil Fruit user. At some point in the past, he consumed the Inu Inu no Mi, pattern: Okuchi no Makami. She is a mythical Zoan-type devil fruit, which allows her to transform into the white fox, known as the guardian deity of Wano.

Yamato can use both beast and hybrid forms, which shows that he has great mastery over his devil fruit. Yamato's strength became evident when he fought Kaido in 1v1, a feat only Luffy could boast of. Not only was he blocking Kaido, but he was also able to deal damage to him. Now that his power level has been made clear, it's time to discuss how he would negatively affect the Straw Hat Pirates' trio of monsters.

Yamato's impact on the monster trio

Oda made the right choice by keeping Yamato in Wano

The monster trio consists of Luffy, Zoro and Sanji. All three are extraordinary fighters that the rest of the crew members can rely on in case of danger. Being the captain, Luffy is obviously the strongest of the three. He is followed by Zoro and then Sanji. Luffy has access to all three types of Haki and their advanced versions. Zoro can also use all types of Haki, but he does not have mastery over them. Meanwhile, Sanji only has access to two types and, like Zoro, cannot use the advanced versions.

So, if Yamato were to join the crew, he would be the strongest member after Luffy. This would completely destroy the dynamic of the trio of monsters. Sanji would be kicked out completely, while Zoro would be moved to third place. Luckily, Oda showed his common sense and decided to keep Yamato in Wano. However, fans shouldn't rule out the possibility of Yamato joining the Straw Hat Pirates in the future.