Orga Itsuka is the leader of a private security company called Tekkadan, and just like every other member of Tekkadan, Orga Itsuka is also an orphan that was forced to work as a slave on mars. Tekkadan is his way of giving hope and a future to his fellow forgotten orphan children. However, their jobs require them to make new friends and enemies on a daily basis. Not only that, but they also have to carefully maneuver the intricate world of politics that happens all around them.

Unfortunately, one of those enemies is finally desperate enough to stop in front of Tekkadan's headquarters, and begin spitting bullets at Orga who happened to walk together with another orphan child at the time. Orga instinctively turns his back toward the assailant to protect the little kid. As a result, Orga Itsuka is showered with so many bullets and dies on the spot. His death is one of the most pivotal moments in the series and frankly speaking, nobody ever thought that a character as important as Orga would die. And that is what makes it such a memorable moment.

When Cell achieves his complete form, it is not an exaggeration to say that he is the strongest being on earth. That being said, Goku believes that his son, Gohan, is way more powerful than everybody else, including himself. This is why he decided to let Gohan fight Cell. And as expected, Gohan manages to push the horrid creature to within an inch of his life.

However, a brief moment of carelessness allows Cell to gather up his remaining power and turn himself into a time bomb that can instantly annihilate everything on earth. Not only that, the slightest touch can trigger the explosion, which prevents anybody from doing anything to him.

Failing to come up with any other solution, Goku decides to teleport Cell to King Kai's little planet. Just mere seconds later, Cell explodes and kills Goku and everybody in the vicinity. Goku doesn’t hesitate to sacrifice himself because he knows his son is strong enough to defend the earth in his absence.

The members of the survey corps are masters at getting close to the titans and slicing open their napes. However, that particular tactic is useless against the beast titan who can launch countless projectiles from afar. It is basically similar to trying to fight a heavy artillery unit with a sword.

However, there is still a sliver of hope for victory in the form of Humanity's Strongest Soldier, Levi Ackerman. Erwin Smith, the commander of the survey corps, and the rest of the members know that Levi can take down the beast titan, as long as he can get close to it. So that is what Erwin decided to do.

In a somber yet fiery voice, Erwin asks his soldier to march with him towards the beast titan. He asks them to be the decoy so that Levy can silently get closer to the beast. So Erwin rode with his soldiers straight on to certain death while countless debris the size of a cupboard flew towards them, killing them all one by one, including Erwin himself. This remains to be the most heroic death in the entire series.

When Kushina gives birth to Naruto, the nine-tailed fox is in the middle of attacking Konoha. In order to save Konoha, Minato instantly teleports the nine-tailed fox to the closest place that bears his teleportation mark, which happens to be the small clinic where Kushina and their newborn son, Naruto, are located.

The nine-tailed fox wreaks havoc on everything surrounding the area. But when he is about to put his claw into baby Naruto, both Kushina and Minato jump in front of their son and are pierced by the claw instead. In his dying moment, Minato sealed half of the nine-tailed fox's chakra to himself, and the other half to his son.

At the same time, he also put some of his and Kushina's chakra into the seal so that they both may appear when Naruto finally tries to control the nine-tailed chakra in the future. This is just a simple storyline in the whole grand scheme of things, but it is easily one of the most emotional moments in the entire series.

Portgas D. Ace is Luffy's sworn brother and the 2nd division commander of the Whitebeard Pirates. When Ace loses a match against a traitor called Blackbeard, he is captured and given to the world government who intends to hold a public execution for him.

Needless to say, Luffy and the entire Whitebeard Pirates Grand Fleet come to rescue Ace from the blade of the executioner. They have to fight their way into the furthest part of the Marine HQ in Marineford in order to save Ace while being swarmed by strong Marine officers, including the three admirals, at the same time.

It is an impossible task no matter how you look at it, but Luffy somehow manages to go through this chaotic battlefield and free Ace from his seastone shackle. However, just when they intend to flee towards the sea, one of the most ruthless admirals named Akainu suddenly appears before them. Just before Akainu's magma fist got to Luffy, Ace stood out before his brother and received the full brunt of the deadly attack. The death of Ace sends a terrible shock not only to the other characters but also to the readers all over the world.