Is Tanjiro using the fire god's breath dance and Nezuko using his ability a deus ex machine? Does it have foreshadow?


In chapter 19 against Rui the dance and the sanguine explosion take place, do
they have a past reference? or is he a deus ex author's error? I[![enter image
description
here](https://i.stack.imgur.com/mdNU1.jpg)](https://i.stack.imgur.com/mdNU1.jpg)
need your help




It could be considered a [Deus ex
machina](https://en.wikipedia.org/wiki/Deus_ex_machina). To quote from its
definition:

> ...a plot device whereby a seemingly unsolvable problem in a story is
> suddenly and abruptly resolved by an unexpected and unlikely occurrence.

The 'unsolvable problem' here would be the fight between Rui and Tanjiro since
the latter was on the verge of losing to the former's seemingly overwhelming
strength. Tanjiro then discovers a new skill using a different breathing
technique and while it may not have 'abruptly resolved' the problem, it was
'unexpected and unlikely' since he was only shown to use Water breathing
techniques and it was enough to buy time for reinforcements to arrive, as seen
in **Episode 20**.

But was this an error? I don't think so. This event was meant as the beginning
to unraveling of Tanjiro's past. Personally, I think it was a good way since
it makes you curious about the background of Tanjiro's family, whether they
were really just a family who makes charcoal or was there something more since
his father seems to know breathing techniques. Was there foreshadowing before
this? None. Rather, _this is the foreshadowing to something later on in the
storyline_. All the unanswered questions from this part will eventually be
answered later on as the story progresses. You can read the manga or wait for
the anime to adapt everything.

