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.

Hashirama Senju Heroes+BreezeWiki

Naruto: Shippuden (season 17) - Wikipedia

Death of the Strongest Hokage after Naruto May be Due to Overusing One of Konoha's Greatest Jutsus - FandomWire

The Third Hokage used the Dead Demon Consuming Seal to defeat Orochimaru

Four Hokage Battle Royale, Death Battle Fanon Wiki

Four Hokage's Return! – Orochimaru's Edo Tensei Enabled! – Naruto 618

Reaper Death Seal! - Leaves in the Wind: Hashirama's Will

Who killed hashirama? How did he die? : r/dankruto

Hashirama Senju by Robert-Sennin on DeviantArt

Pokemon Hashirama 18

List of Naruto characters

100+] Reaper Death Seal Wallpapers

How was Hashirama Senju sealed inside the Reaper Death Seal? - Quora