Yes this is a RANT. If you don’t want to read the rant then skip this and move along. I am basically stating my opinion here. If you want to discuss this topic with me, you’re more than welcome to message me. As I would rather not let this perpetuate into some potential flame war. Now with that said, onto the rant.
Taken from the not-very-reliable-Wiki:
Yōketsu (妖穴, “Vortex of demonic energy”) visually it manifests in the form of a whirlpool behind demon-like characters that are visible to just a few. This vortex can be cut and its effect is an instant-kill upon the demon whose yōketsu is being cut; Inuyasha’s Dragon-scaled Tessaiga had this ability.
This attack first shows itself in vol 43 of the manga then is explained better in vol 44. At least, it’s explained according to the authors logic, which is where my rant lies here.
This whole thing doesn’t sit well with me. Not to over-analyze the possible science involved here, but to me an attack that makes striking a whirlpool of youkai energy lead to an instant kill is absurd. Without going into the theories of supernatural creatures, i’ll instead focus on the flow of energy as it appears in the natural world and Occultism.
My opinion, energy flows in two ways, a creature or entity that can harness such energy by pulling it in from the environment around them or generates it within themselves and it flows out of their forms as they tap into it. In other Words Chakra and Chi (also known as Qi)
In a nut shell the two energies are almost the same, both exist as power points within the body. However, in my understanding, Chi is viewed as the life energy within that must be drawn out while Chakra’s are effected by earth energies such as vortices.
So what happens when one of these is cut?
Going along with the theory that you have a creature who is pooling so much energy around them that it’s forming whirlpools outside of their body. With the nature of Chi who’s source is within the body, if you cut off the energy that extends from the body, would that lead to an instant kill? The source is inside the body not out. Cut the body and …well…forget the chi, one mortal wound and your finished.
How about Chakra then? Chakra can pull energy in but theoretically it’s not directly connected to the life energy. What if you cut off the flow of energy feeding into the Chakra? You cut off the flow of energy to the Chakra. Unless the creature was 100% dependent on this energy, I don’t see it resulting in an instant kill.
I’m only scratching the surface here on Chi and Chakra. There is tons of research material out there for these theories, but I decided to keep it simple and stick to the basics for this little rant.
So really, in my opinion the Yōketsu attack leading to an instant kill is utter Bull Shit. Not sure what Rumiko Takahashi was thinking when she came up with this idea, but to me it seems half-baked. Not that she needs to explain anything she includes in the story. I fully understand that. But this bit just bugged me.
Then again most of the attacks Tetsusaiga picked up during it’s “upgrade” arcs irk me to some degree as well.
Alright I’m done.
Yeah, the youketsu wasn’t particularly well explained in any incarnation of the series.
The youketsu, then, is the conduit through which this mass-energy exchange takes place. Destroying it severs the link between a youkai’s energy body and physical body. Because the original power of Dragon-Scaled Tessaiga is to absorb youki (i.e., a youkai’s energy body), hitting the youketsu with it is essentially plugging it directly into a youkai’s life source and going “sluuuurp”, causing the youkai’s physical body to disintegrate due to no longer having anything to sustain it.
Although, since I’m more of a physics nerd than a mythology nerd, that was my take on it. ^_^*