Sun Blade

The Sun Blade is a storied weapon hammered out in the distant past on a landmass that has since vanished under the sea, and it has moved down the generations through the council of swordsmen. Its twin is the Moon Blade, and old lore promises that anyone who commands both at once will wield strength beyond compare, a legend the Council of Swordmasters has chased for ages. Nichirin keeps the sword tucked inside a pocket dimension within his pearl necklace and hands it to Atomic Samurai amid the fight against the Monster Association.

A spirit lives within the Sun Blade and reaches its wielder through telepathy, weighing whether that person deserves its might. Only when a swordsman reaches a peak of concentration can the weapon be pulled free of its sheath, as Atomic Samurai shows. Drawn, it sharply boosts his ability, letting him carve through one of Homeless Emperor's biggest energy spheres and lop off Golden Sperm's forearm, and the blade can even turn pliant and extend its reach. That power comes with hazards: it may seize hold of the wielder's mind, and leaning on it too hard brings on heavy exhaustion, which Atomic Samurai feels after trading blows with Golden Sperm.

Atomic Samurai is the sword's current bearer, having received it from its former keeper Nichirin. A note of wordplay surrounds it: the blade's name, written 日輪, is spoken the same as the swordmaster Nichirin's name, both carrying the meaning of the sun, with the manga separating them by writing one in kanji and the other in katakana.