Hachimaru is a weak and sickly boy who has been connected to a machine all his life, and dreams of being a samurai. His encounter with Daruma, a cat samurai, allows him to receive the power of the war god Fudo Myo-o and become a samurai, kicking off his adventure.
Samurai 8: The Tale of Hachimaru provides examples of:
- Arc Number: Eight, as the title indicates. Hachimaru has that number in his name, he's the eigth person Daruma has scouted, his first real meal is eight takoyaki (octopus dumplings), and "Nanashi" hadn't talked to a human in eight years.
- Cyborg: Samurai are cyborgs. Their bodies are entirely robotic and instead of spines they have a memory unit known as a key.
- Mythology Gag: The VR headsets heavily resemble the Shinobi Headbands of Naruto.
- Ninja Pirate Zombie Robot: The premise of the story is cybernetic samurai. Daruma himself is a mechanical cat samurai.
- Samurai: Samurai are individuals chosen by the war god Fudo Myo-o's locker ball with the duty to protect the galaxy. They are considered to be above bushi (human warriors).
- Scenery Porn: Chapter 2 provides two hyper-detailed splash pages where Hachimaru flies over the landscape with Hayatarou and gets to see the bustling town he lives in for the first time in his life.
- Soul Power: Samurai have special souls that serve as their real weapons instead of their sword.
- War God: The war god Fudo Myo-o who created the locker ball, a small star that turns those compatible with it into samurai.
- World's Greatest Warrior: The female grandmaster of Daruma, who guards the whole galaxy and sends Daruma on his quest to find 7 keys for Pandora's Box.