There’s tons of different elemental breathing styles in the Demon Slayer universe. So why does Tanjiro have water powers?
Tanjiro has water powers because he was trained by the former Water Hashira, Urokodaki. He was also recommended for the training by the current Water Hashira, Giyu.
Giyu finds the boy by complete coincidence. Tanjiro learns water breathing because it was the only training available to him at the time. He learns later that fire breathing is his more natural elemental breathing style, but Tanjiro still retains the water skills he learns.
Tanjiro learns to use his water powers
In chapter #3, Water Hashira Giyu writes a letter to his sensei and previous Water Hashira, Urokodaki, about Tanjiro. The letter says that he’s sending Urokodaki a boy who claims he wants to be a demon-slaying swordsman.
| RELATED: How Did Nezuko Become a Demon? |
The letter continues and says that Tanjiro had the courage to fight Giyu unarmed. Giyu gives context on how he met Tanjiro, explaining he’s the survivor of a demon attack and his sister, Nezuko, has become a demon. Yet, Nezuko chooses not to attack humans and covers her fangs with bamboo.
Giyu writes that he senses something different in Tanjiro and Nezuko than the others. Like Urokodaki, Tanjiro has a sharp sense of smell. Giyu suggests that perhaps Tanjiro could be worthy of carrying the water breathing traditions.
“Please train him,” Giyu wrote. “I know this is a selfish request, so please forgive me.”
Once Tanjiro arrives and is taken under Urokodaki’s wing, he learns the ways of the water breathing. Despite fire breathing being Tanjiro’s natural element, he still learns the ways of water breathing. He has no way of knowing at this time as to what his natural elemental breathing style could be. Tanjiro is the first swordsman in his family, as far as he knows.
So that’s the answer. Tanjiro has water powers because it was the first demon slaying training available to him. The modern Water Hashira recommends him to train under the retired Water Hashira, so Tanjiro just fell into that elemental style.