How was Hashirama in the Reaper Death Seal in Naruto?

The Reaper Death Seal, initially created by the Uzumaki clan, is one of the few forbidden jutsus in the Naruto universe. It is said that those who use the Reaper Death Seal will have to submit their soul to the Death God as well. In Naruto, there are only two known instances where the Reaper Death Seal has been used.

It was first used when Obito, under the guise of Madara, infiltrated Konohagakure in an attempt to steal Kurama, the Nine-Tailed Fox. The caster of this jutsu was Minato Namikaze, the then Hokage and Naruto's father. He used this justu to trap Kurama.

The second time it was used was when Hiruzen Sarutobi, the Third Hokage, was fighting against the reanimated clones of Hashirama and Tobirama Senju.

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What happened to Hashirama Senju in Naruto?

It's unclear how the First Hokage died. However, he was reincarnated by Orochimaru many years later when he attacked Konohagakure. Orochimaru used the Reanimation Jutsu created by Tobirama Senju. That said, Orochimaru was unable to perfect the jutsu and could manage to reanimate both Hashirama and Tobirama, but only to 20% of their true potential.

He used these reanimated bodies to launch an attack on the Leaf Village. Despite being at just 20% of their power levels, both these individuals were very strong, and Hiruzen Sarutobi found it difficult to keep up with the former Hokages.

Despite being old, he still managed to put up a good fight and eventually cast the Reaper Death Seal, sealing both Hashirama and Tobirama inside Shinigami's stomach. While this jutsu took his life, Hiruzen managed to damage Orochimaru's arms completely.

This is how Hashirama ended up inside Shinigami's belly. However, he was brought back to life once again by Orochimaru. With assistance from Kabuto, Orochimaru was able to perfect the Reanimation Jutsu and bring back Minato and Hiruzen alongside Hashirama and Tobirama.

His prowess with the jutsu had improved over the years, and this time, the reanimated bodies had way more than 20% of their power restored.

During the Fourth Great Ninja War, all four Hokage were very influential and were a strong reason why the Ninja Coalition was able to keep the Zetsu and Ten-Tails at bay. It was only after their involvement in the war that the Ninja Coalition was able to make a comeback on the battlefield.

Overall, this justu requires a lot of dedication and focus to execute perfectly. It comes at a great price as well. Both times this jutsu was executed, the caster paid a huge price. Hashirama's fate was unclear after the war as well. Since he was reanimated, it's expected that the jutsu will wear off, and he will go back to being dead again.

That said, the Reaper Death Seal jutsu remains one of the deadliest jutsus in the entire Naruto universe. There's a reason it's considered a forbidden jutsu, and thankfully it will continue to stay that way for generations to come.