The sword breathing techniques get explained by a former Flame Hashira.

Tanjiro uses Hinokami Kagura against Daki in the most recent trailer.

Hold up -- are y'all listening to this new Demon Slayer theme song? Seriously, it rocks. I didn't think anything would come close to LiSA's Gurenge from the first season, but here we are. 

Though we are only two episodes into the Entertainment District Arc, it's already running at full throttle with humor, intrigue and spectacular animation. The Sound Hashira Tengen Uzui has picked up our favorite swordsmen trio and is infiltrating Yoshiwara, the Entertainment District, which, by the way, was a real district in what's now present-day Tokyo. 

The first episode of the arc formed the crux between the fallout of Mugen Train and the beginning of this new mission. And in that first episode, we hear from Kyojuro's surly, alcoholic -- but obviously grieving -- father, Shinjuro Rengoku, who's a former Flame Hashira. 

Shinjuro reveals some interesting details about a sword breathing technique we hadn't heard of before: sun breathing. Here's what we found out and how it relates to the other breathing techniques. 

Every year, Tanjiro's family performs a Kagura dance to Hinokami, perhaps a deity of fire. Tanjiro's mom says in season one that their "family works with fire. So, to ward off injuries and disasters, we offer this dance to Hinokami along with our prayers at the start of each year." Tanjiro recalls that his father is able to stay warm in freezing temperatures using the dance. 

On remembering this, Tanjiro uses the Hinokami Kagura in his sword work during a battle against demons Rui and Enmu, both members of the Twelve Kizuki. 

Tanjiro's father performing the Hinokami Kagura.

Shinjuro yells at Tanjiro that sun breathing is the original breathing technique. All the other techniques are just "cheap imitations" of sun breathing. It seems Tanjiro's hanafuda earrings are connected to sun breathers somehow -- at least, that's what the Flame Hashira book said before Shinjuro partially tore it to pieces. 

Tanjiro doesn't know anything about this sun breathing thing. His family members have been charcoal sellers for as long as he can remember, with the history records to prove it. We don't know how Tanjiro's family received the earrings, though we know his father wore them, and Tanjiro inherited them. In any case, sun breathing seems tied to Hinokami Kagura in some way. 

Moreover, we don't know of any sun breathers -- at least not yet. The way Shinjuro speaks about it makes it seem as though it's an extinct breathing form.

Tanjiro's father wearing hanafuda earrings.

Kyojuro tells Tanjiro on the Mugen Train that the five fundamental breathing techniques are fire, water, stone, wind and thunder. All the other techniques are offshoots of those five. The serpent, insect and flower techniques are offshoots of water; mist is an offshoot of wind; sound is an offshoot of thunder; and love is an offshoot of flame. 

And now we now that all these breathing techniques are offshoots of sun breathing.

The sword breathing elements and their offshoots, according to Kyojuro Rengoku.

Like the other techniques, flame breathing is merely an offshoot of sun breathing.

We don't yet know the history behind sun and flame breathing, but we can at least tell that they differ given the subtle distinctions in their visual conceptualization. At least, to the extent that Hinokami Kagura is indeed a form of sun breathing, which hasn't been confirmed yet. 

If you look at Rengoku's flame breathing technique, you can tell that it's more orange in color compared with Tanjiro's Hinokami Kagura (pictured at the top of this article), which has a more reddish hue. 

Kyojuro uses the second form of flame breathing: Rising Scorching Sun.