#breathing styles

When they re used for too long or too intensely, each tehnique has certain effects on the user, that must be overcome or treated after a gruesome battle.

-Water Breathing - channeling the energy for Water breathing rarely affects the user , but it can bring the body temperature too low after prolonged use. The user will feel their fingertips freeze first, then it will affect their movement as they re basically freezing from the inside out. Water Breathing and its derivates (Ice Breathing) naturally use lower body temperatures. The user must be trained to withstand the low body temperature, artery contraction and the temporary high blood pressure that comes with it. Their muscles are also trained to support poor vascularization because of the body's response to cold - vasoconstriction. A skilled Water Breathing user will instinctively train their lungs to be able to function under cold temperatures since the cold air / low body temperature will trigger, in worst case scenarios, the state of shock. Such happens, as we know, when Giyuu uses the eleventh form - Dead Calm, his heart temporarily stops , regaining function only because of Giyuu's training and exceptional physical state.

-Flame Breathing : opposed to Water Breathing, the user might overheat, and the effect takes place faster than other tehniques. With a higher body temperature, the Rengoku family usually tolerates it well, but it can affect them too after using it too long or too intensely. The user must be trained to withstand the higher temperature, higher heartbeat and vasovagal reactions that take place - artery dilation and, if it gets to their cerebral vascularisation, passing out (because of the poor circulation to the brain). Aside from the functional reflexes of the body, the high temperatures , used especially by powerful Flame Breathing users will affect the fluid quantity of the body, the first affected being the nasal secretions (that help us breathe and humidify the air) and the saliva and mucus that coats the pharynx - making it harder to breathe altogether. The Ninth Form - Rengoku (Purgatory) is a form that only the Rengoku family can survive , and even then , they use it as a last resort because they know / expect they will die anyway. (as we saw in Rengoku's fight against Akaza.)

-Thunder Breathing (lightning breathing) - the effects take place fast too, and if the person is not trained or has a lower tolerance for it, it might get fatal pretty fast. The high electric currents that the technique triggers will mess with the heart first, its function relying almost completely on its own electrical function. If the Tehnique tampers with the heart Sinoatrial Node's electrical function, it will trigger potentially fatal arrythmias, that will lead to either cardiac arrest, or fibrilation. The user must be trained to withstand the currents that affect their heart muscle, that will further affect the circulation and life long risk of cardiac arrest. The second organ that will get messed up by the tehnique is the brain, the electrical currents potentially tampering with the transmission of synapses between neurons - which will lead to either passing out or a temporary state of delirium / coma. This only happens after long , intense battles in which the Slayer has overused their Thunder Breathing. Aside from that, the local and immediate effect the tehnique can have on the body is muscle spasms (especially in the legs and arms) , triggered by the non-specific electrical currents that activate the neuromuscular synapses indefinitely (it passes after the receptors have a negative feedback that lowers their sensitivity and number).

The effects are there. You are supposed to be seeing something.

The effects just can't impact the environment.

So Tanjiro and Giyuu cannot start a flood with water breathing. Zenitsu cannot electrocute someone with thunder breathing.

Sun breathing - To learn the strongest breathing you just need two things, which are important. You need to have good and peaceful soul and just not be a greedy and bad person - it'll make things easier to learn, and you need to have a great reflex.

Moon breathing - Without being a samurai before being a demon slayer and slightly dislocated (flexible or whatever) joints, don't even think about learning it.

Stone breathing - Since it takes to know how to handle every weapon but katana, so if you aren't strong enough or you don't know how to do it, just don't try or you'll end up without leg and hand

Love breathing - It's almost as same as stone breathing (in weapons), so mainly you need flexibility

Insect breathing - Speed and thrust strength. Insect breathing is nothing without speed and poison, so to cut (rather pierce) demon's head, you need to pierce and inject the poison (breathing is based on poisons, because on the tip of the katana, there's a small hole which let's poison out, since the poison is inside the sword. Katana with this breathing is very prone to breakage)

Thunder/Rumble breathing - Leg strength and speed. This breathing boosts your speed to the point it's comparison to the speed at which lightning strikes, so if you want that, you NEED to have those things.

Water breathing - It's low-key based on internal peace and arm strength. With calmness, you can achieve much more than normally and with arm strength it's always easier to behead a demon

Wind breathing - Just don't have asthma and you'll be fine

Flame breathing - Nothing. It's the easiest breathing to have and it doesn't take much to learn it, except for fact that you need to understand the techniques because first flame pillar was shit at explaining on a paper how techniques work

Mist breathing - Great sight. Since there's mist around you, you have to see the demon in mist

Flower breathing - Awareness that it can kill you and slightly above the average flexibility.

Beast breathing - Just be prepared to use your raw strength... And flexibility to the point you don't know if you just terribly dislocated your knee or it's supposed to be like that!..

Serpent breathing - Idk, probably flexibility of a snake since everything in this is about snakes

Stelle: Mizunoto (Final Selection), Adaptable Breathing (Usage of other breathing styles, but only the base breathing styles -Fire Water Wind Stone Thunder. (Unable to use Sun and Moon breathing) And only has one form each of these breathing styles, with her sixth form being her own unique star breathing, descended from moon breathing. This form has drawbacks like Lull/Dead calm or Kanao’s flower breathing final form. As it heats up Stelle to rather extreme temperatures and with that comes the risk of heat stroke.

March 7th: Mizunoto (Final Selection) Frost Breathing. Like Inosuke, was born in Douma’s cult, and has no memory of that time in her life, only having memories of running, blood and that camera clutched in her hand. She later ran into a Hinoe named Himeko, who took her in and introduced her to the demon slayer corp. She chose her name after the date Himeko found her.

Dan Heng: Mizunoto (Final Selection) Water Breathing. Secretly from the Swordsmith Village, with his Nichirin sword being forged by his twin brothers best friend, who, now being a demon, blames him for his twins death. As the sword meant for his twin was given to him. And with nothing to defend himself with, Dan Heng’s twin died to the same demon that turned his best friend into one. (Uppermoon 5 Gyokko)

Himeko: Hinoe and Tsuguko of Rengoku Kyojuro. Flame Breathing, completely immune to most types of poison, as she consumes it regularly with coffee. Has a specialised Nichirin kusarigama. Was the slayer who found March 7th. Sent out to investigate possible demon activity in the area, luckily did not encounter upper moon 2. Exceptional navigational skills, owns a family heirloom of a small model train which is the last thing she has left of her family.