From despicable slave trades to murderous man hunts, One Piece has some of the most disturbing and heartbreaking moments in anime.

10. Luffy Feels Guilty About Shanks Losing His Arm

Episode 4: “Luffy’s Past! Enter Red-Haired Shanks!”

In a major flashback sequence, One Piece fans saw how Luffy began his adventure as a rubbery pirate captain. As a child, Luffy ate the Gum-Gum Fruit, and at the same time, mountain bandits were terrorizing the town. It all reached a climax when Shanks saved Luffy from the same sea king that ate Higuma, but Shanks paid a heavy price for his heroism.

Shanks’ left arm was bitten clean off, and Luffy was reduced to tears, wracked with guilt about his role in Shanks’ injury. That was a rough start for Luffy’s adventures, but he moved past it and started training so he could follow Shanks’ example as a pirate captain. At least that scene wasn’t dark for Shanks, who didn’t feel bad about losing a limb to save Luffy’s life.

9. Luffy Tells Nefeltari Vivi That She Can’t Stop People Dying In War

Episode 104: “Luffy vs. Vivi! The Tearful Vow to Put Friends on the Line!”

The Alabasta saga was Luffy’s first adventure in the Grand Line, and for the first time, Luffy saw a full-scale war unfold. The villainous Sir Crocodile orchestrated a bloody civil war, but Princess Nefeltari Vivi was confident that she could suppress the conflict and prevent any deaths. Luffy, however, wanted to go after Crocodile and let the bloodshed happen in the meantime.

Luffy and Vivi got into a heated argument about it, to the point Luffy actually struck Vivi with a low-power punch to emphasize his point. It’s always a dark scene when someone kind like Luffy attacks an innocent hero like Vivi, but Luffy felt it was necessary. He argued that it’s naive to think no one will die in war, and Vivi reluctantly agreed.

8. Luffy Fights For Vivi Even If It Means Death

Episode 125: “Magnificent Wings! My Name is Pell, Guardian Deity of the Country!”

Luffy lost to Sir Crocodile twice during the war for Alabasta, but when the giant bomb started ticking down in Aluburna’s city square, Luffy knew he had to act despite the danger. He went after Sir Crocodile, who had gone underground, and Luffy fought that Warlord of the Sea with all his might. Luffy was the weaker fighter, but he had grim conviction on his side.

Luffy wasn’t smiling or carefree in that fight. He was outraged that Crocodile had destroyed Vivi’s happiness, and Luffy vowed that even if it meant all the Straw Hats would die, they would fight for Vivi’s beloved kingdom. It was both inspiring and rather dark to see Luffy wager everyone’s lives so casually just for a fighting chance at defeating Crocodile.

7. Luffy Fights His Friend Usopp At Water 7

Episode 236: “Luffy vs. Usopp! Collision of Two Men’s Pride!”

In the Water 7 saga, the Straw Hat pirate crew turned on itself for the first time. Their ship, the Going Merry, was falling apart and needed to be replaced, but Usopp couldn’t accept that fact. He and Luffy got into a bitter argument over the Going Merry‘s fate, to the point they agreed to a formal duel to see who’d get their way.

When friends fight friends in action anime, there is no winner, no matter how the fight turns out. Luffy and Usopp both explored their darkest side and watched their friendship crumble as they clashed, and the other Straw Hats could only watch with dismay. It was a rare moment of Luffy losing rather than gaining a friend, but the events of Enies Lobby would change that, fortunately enough.

6. Luffy Punches Saint Charlos To Protest The Slave Auctions

Episode 396: “The Fist Explodes! Destroy the Auction”

In the Sabaody Archipelago story arc, things went from carefree to shockingly dark for Luffy and his friends. Luffy was horrified that the World Government’s elite bought and sold people at auction houses, including the lovable mermaid Camie. Luffy was seething with righteous rage, and when the detestable Saint Charlos appeared, Luffy couldn’t hold himself back.

It was a dark but also satisfying moment when Luffy unleashed his fury on that Celestial Dragon, slugging the smug Saint Charlos to protest the institution of slavery. It was a horribly dark moment of worldbuilding, where the World Government allowed the slave trade to flourish, but at least Luffy had a proper response to Saint Charlos’ role in it all.

5. Luffy Is In Denial About Being Poisoned By Magellan

Episode 437: “For His Friend! Bon Clay Goes to the Deadly Rescue!”

Luffy raced to the underwater prison Impel Down with Boa Hancock’s aid to rescue his foster brother, Portgas D. Ace. Unfortunately, Luffy lost his fight against the warden Magellan and his Venom-Venom Fruit. Luffy was dying from powerful poisons as he was locked up in the frigid level 5.

However, Luffy was in total denial, trying to continue his mission with willpower alone. For once, Luffy’s indomitable will was helpless, and his impending death was certain. It was tragic to see Luffy struggling in vain in that powerless state, all while his new cellmates scorned him for it. If it weren’t for Bon Clay’s rescue, Luffy would have died in miserable vain.

4. Luffy Agrees To Let Crocodile & Other Level 6 Prisoners Go Free

Episode 443: “The Ultimate Team Has Formed! Shaking Impel Down!”

Luffy’s mission finally resumed when the new hero Emporio Ivankov boosted his hormones to fight off Magellan’s poisons. Luffy’s next stop was level 6, where the world’s worst criminals resided, including Sir Crocodile himself. Luffy protested at first to releasing Crocodile as an ally, but Luffy was convinced to accept that plan, if only barely.

No one can blame Luffy or Ivankov for taking drastic measures in their moment of desperation, but even so, it was a dark move on their part. Releasing Crocodile had serious consequences later when he teamed up with Dracule Mihawk to form Cross Guild, an organization that put bounties on Navy officers, including the innocent Coby.

3. Luffy Sees Ace Die Before His Eyes

Episode 483: “Looking For the Answer! Fire Fist Ace Dies on the Battlefield!”

The incredible Marineford War erupted when the Whitebeard Pirates crew arrived to fight the Navy’s assembled forces, but Monkey D. Luffy wasn’t there to win a war. He focused on finding and rescuing Ace, and the foster brothers were reunited at last. That is until Admiral Akainu dealt a magma punch that sealed Ace’s fate.

To Luffy’s horror, Ace died before his eyes, and not even Ace’s kind parting words could soften that emotional blow. Luffy could only cry out in despair and grief, so it fell to new heroes like Trafalgar D. Water Law to step in and get Luffy out of there. It was a low point in Luffy’s adventure, one that led to another dark scene just a few episodes later.

2. Luffy Fights Jimbei To Process His Grief

Episode 505: “I Want to See Them! Luffy’s Mournful Cry!”

After some flashbacks, Luffy was seen at Amazon Lily in rough shape, physically and emotionally. His body was healing after the trauma of that war, but his heart was still in pieces, unable to process Ace’s shocking death at Marineford. Luffy lashed out at his new ally Jimbei out of sheer frustration, but it was for nothing.

Jimbei restrained the grief-stricken Luffy and finally convinced Luffy to think about the people he still had — his Straw Hat crewmates. Luffy reached rock bottom in that scene, feeling alone and powerless, only to feel hope rekindled in his heart once again. It was a turning point in Luffy’s adventure, a harsh lesson that sometimes, even the greatest pirates will lose people.

1. Luffy Faces Defeat At Kaido’s Hands At Onigashima

Episode 1070: “Luffy is Defeated?! The Determination of Those Left Behind!”

In the Wano saga, Monkey D. Luffy used everything he had to fight powerful foes like the mighty Emperor Kaido, but not even the power of Gear 4 and Haki could take down Kaido in the Onigashima battle — not at first, anyway. Luffy fought heroically, but he was ultimately vanquished, crashing down to the rocky ground in bitter defeat.

One Piece fans had seen Luffy lose before, but Luffy’s defeat at Kaido’s hands felt more final, more brutal, and more nightmarish than anything before it. More than ever, all hope seemed lost, and not even Luffy’s allies like Trafalgar Law and Eustass Kid could make much headway against the Emperors, suggesting the samurai coalition was about to lose for good. Fortunately, though, the very next episode would usher in Luffy’s Gear 5 transformation to turn the tables.