'One Piece' chapter 840 spoilers: New chapter reveals the reason behind the Vinsmokes' exceptional strength

In the latest chapter of the "One Piece" manga, Sanji's origin has been revealed along with the reason behind his deep hatred of his own family.

"Iron Mask" picked up where the previous chapter left off and shed light on the origins of the Vinsmoke siblings. Yonji told Sanji that their father, Judge, used to be hailed as a brilliant scientist who worked with Vegapunk on the development of high quality weaponry. They soon discovered and took quick interest in cloning and genetic modification but their research project was shut down. Vegapunk was arrested before the project could even be applied to actual specimens.

Judge escaped the hunt and soon applied his genetic know-hows on his own children, who all grew up to be exceptionally strong and skillful, except for Sanji. It seemed that Sanji's genes defied any enhancements and modifications and he remained to be a weak and ordinary human being with a natural tendency for compassion and empathy. Wanting to start anew and forget that a weakling like Sanji was ever born out of his own lineage, Judge had Sanji imprisoned in a dungeon with an iron mask covering his face.

In the present, Judge had been manufacturing clones of select soldiers of the Germa army so that a ready replacement would be available when the army gets depleted. These were the cloned men that Sanji saw inside what Yonji referred to as the Soldier Depot.

Sanji also had a chance to avenge Cosette on Nijji but was eventually beaten to the ground after Ichiji reminded him how easy it would be for the Vinsmokes to take Zeff's life.

GameNGuide speculated that the true potential of the Vinsmoke siblings will be revealed in chapter 841. Sanji may also eventually live up to his lineage and awaken his long dormant skills once he is triggered to respond to his brothers' threats without being held back by their threats on his friends' lives.

Movie News Guide cited fans' surprise that Luffy's fight with Cracker has not been continued yet. The fight's conclusion may be featured soon after the Vinsmoke's backstory has been told.

"One Piece" chapter 841 will be released next week on the "Weekly Shounen Jump" magazine.