He can keep up in a fight against any demon, but what is Tanjiro’s rank in the Demon Slayer Corps?
Tanjiro’s rank in the Demon Slayer Corps is Kanoe, the fourth up from the bottom. He doesn’t receive a higher rank for the remainder of the series.
His rank is specified during a conversation with Inosuke held during the Entertainment District arc.
Inosuke tells Tanjiro about their Demon Slayer Corps rank
In chapter #75, Tanjiro and Inosuke meet on an Entertainment District rooftop to discuss the location of a demon. Tengen Uzui, the Sound Hashira and supervisor on their mission, says he may have dragged them into danger.
Tengen reveals that he hasn’t heard from Zenitsu since last night. There’s likely an upper-rank demon in the area, so Tanjiro and Inosuke are told to abandon the mission for their own safety. Recently, an upper-rank demon was able to defeat the powerful Rengoku, so there’s little faith in slayers below the rank of Hashira to ever take one down.
Tanjiro suggests to Inosuke that they’re not trusted because of their place in the lowest rank.
The 10 ranks in the Demon Slayer Corps, from lowest to highest, are Mizunoto, Mizunoe, Kanoto, Kanoe, Tsuchi-noto, Tsuchi-noe, Hinoto, Hinoe, Kinoto, and Kinoe.
Inosuke explains to Tanjiro that they’re four up from the bottom. They were originally Mizu-noto, but now they’re Kanoe. The promotions came as a result of their time demon-hunting on the Mugen Train with Rengoku, as well as passing the final selection exam.
Then, Inosuke demonstrates a demon slayer’s ability to display their own rank. By saying a password and flexing, your rank will appear somewhere on your skin. Inosuke says his password and shows his rank on his hand as a demonstration.
That special Demon Slayer Corps mark uses a special technology called Wisteria Flower Engraving, Inosuke says.
So that’s the answer. Tanjiro’s rank in the Demon Slayer Corps is Kanoe, fourth up from the bottom.