The first time we see a bullet hit Kirito's light-saber the bullet melts. Next episode we see this happen again although this time the sword cuts the bullet in 2 half's. How is this possible?

Episode 5

Episode 5

Episode 6

Episode 6

  • 2
    I was wondering if it could be something due to the widths of the bullet, but a .50cal (bullet, not cartridge!) is only about 12.7mm wide, or a third again wider than a standard 9mm. Commented Mar 20, 2015 at 9:29

5 Answers 5


Lordmau5's theory is quite interesting, but it doesn't quite match the visual appearance of the sword as described in the light novel.

I stared at it for a while, and found that the sword itself didn’t have any direction as the entire circular section was just like a long and thin cylinder.

* From Sword Art Online Volume 5 - Chapter 6, after Kirito bought the sword and activated it for a test run.

The corresponding scene in the light novel (also in Volume 5 - Chapter 6) doesn't say anything about the bullets melting:

The enemy’s rifle’s muzzle suddenly let out an orange spark.

During this time, the blade of the light saber blocked the lines of the first and second bullets with pinpoint accuracy.

*BA-BAM!!* The surface of the light saber let out two bright orange sparks. The moment I noticed this, my right arm immediately pointed the photon sword onto the third and fourth bullet lines at a lightning quick speed. Then, the sound of the bullets being deflected off the intense energy could be heard again.


5...and that’s the 6th one! After deflecting all the bullets that could have hit me successfully, I kicked the ground hard with all I’ve got to cover the remaining distance between us.

The next scene (where his opponent ran out of ammo and had to change magazine) starts right after the text cited above. Therefore, the scene in episode 5 of SAO II is most likely something added in the anime to explain how the bullets are neutralized and to impress viewers, since the viewer can't see how Kirito neutralize the bullets if the scene is animated at real world speed.

The bullet being cut in half in episode 6 is actually described in Volume 5 - Chapter 7, though:

From the Hecate’s large muzzle break came orange flames. On the other side, the blue white lightning cut through the dusk darkness.

Shining like shooting stars, two small lights split to the left and right, flying far away.


It was cut apart.

At the moment the bullet fell to the ground, Kirito’s lightsaber slashed upwards, and cut the 50-caliber bullet that was supposed to be a fatal hit. The two shooting stars that Sinon saw, were fragments of the bullet that were cut by the high concentration energy blade, and flew pass either side of Kirito behind him.

Note that it doesn't say anything about the bullet being cleanly split in half as shown in the anime.

I couldn't find any explanation on how the sword works in the light novel, though, and with so little information, we can only guess why the light saber would deflect bullet in one scene, and cut the bullet in half in another.

  • But then if it at all obey real world physics, all of the bullet would just bounce off due to the leidenfrost effect.
    – DarkDestry
    Commented Apr 5, 2015 at 14:00
  • @DarkDestry: Right, but the light novel seems to treat the light saber as an extremely durable sword. (Well, there is an experiment showing the katana can cut bullet, and I assume deflecting bullet is also possible). Anyway, trying to offer real life explanation to a fictional weapon is not going to work, since we need to speculate how the weapon is made feasible.
    – nhahtdh
    Commented Apr 5, 2015 at 15:09
  • @nhahthd Yes it is proven that a blade can split a bullet, and I agree with your conjecture. But then to all of SAO's depiction of possible repercussions of virtual reality technology, this just seem like a bad plot hole. Or one plausible explanation is that the VRMMO package - the seed, has its weapon basis built upon bladed swords and not cylindrical plasma beams which can cause projectiles to behave differently in different circumstances, such as when the "beam" is angled differently. Just my theory here...
    – DarkDestry
    Commented Apr 5, 2015 at 18:48

It could be possible that the light-saber isn't a full cylinder, but more sword-like.

It's kinda hard to explain, but I'll try anyway:

If you take a look at this sword I found on Google images (I literally just googled for "sword"), you can see that the front of it is wider. The edges of the sword are thin and sharp, so it can properly cut.

Therefore, my theory is that Kirito blocked the bullet with the wider side in Picture 1, whereas he cut the bullet with the edge of the sword in Picture 2.


One could argue the shape of the bullet/it’s velocity could have an effect on how the bullet would react when coming in contact with the photon blade. From my understanding, 9mm slugs have a rounded head, and fire much slower from a hand gun/smg than a .50 caliber round from a sniper rifle. The 9 mm bullet is designed to mushroom on impact for fragmentation. The .50 caliber bullet as far as I know is meant to punch a whole clean through without the fragmentation. So if you think about the way the bullet reacts to hitting its target, it makes sense that the 9mm bullet would be batted off, and the .50 cal would be sliced in two because it would be pushing/cutting past the “blade” and the 9 mm would develop wider surface area as it mushroomed on impact. The heat from the photonsaber probably kept it from breaking into a ton of tiny metallic shrapnel bullets on impact as well.

  • You may want to also address the question of why one melted and the other didn't.
    – kuwaly
    Commented Apr 15, 2018 at 20:40

The most likely case is that because in the first situation Kirito's blade was standing still it melted while in the second it was in motion causing it to cut in half

  • Well, this is certainly what I imagine to be a possible explanation. In the first one, the blade is not standing still (it's just that the scene is slowed down so viewer can see what's happening), but the bullet is close to the source. The second case we don't see what is happening, but it's probably cut by somewhere near the tip of the sword?
    – nhahtdh
    Commented Mar 23, 2015 at 1:52
  • He is changing at the guy who is shooting at him, not standing still.
    – Alagaros
    Commented Mar 23, 2015 at 16:55
  • I was referring to kirito's light saber not kirito himself. - Alagaros Commented Mar 25, 2015 at 0:07

Theory: the saber is actually a sword but it is re-textured. It looks like a cylinder because it generates a light through the whole sword.

Example, well a bad one

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