The final selection is the turning point for aspiring demon slayers to join the ranks. But when the survivors were chosen, someone was missing. Why wasn’t Inosuke at the final selection?
It turns out Inosuke actually was at the final selection. According to Zenitsu, Inosuke passed the exam so quickly that no one took notice of him. He was the fastest person to run up and down the mountain.
That means that Inosuke did participate in the same final selection as Tanjiro and Zenitsu, but didn’t receive any screen time. This was likely done to create a more dramatic entrance during the Drum House Arc, as introducing both Inosuke and Zenitsu at once could be too overbearing from a writing standpoint.
Zenitsu Answers Where Inosuke Was During The Final Selection
Ah! That person is… I heard his sound just now so I know… The 5th person that qualified… He was the fastest person during the final selection to go up and down the mountain!! He’s a hotheaded sort of person!!
Zenitsu Talking About Inosuke | Chapter #26
During the final selection, it’s implied that those who survived are Tanjiro, Zenitsu, Genya and Kanao. We don’t find out until Zenitsu remembers Inosuke’s sound that he also participated and survived in the selection, albeit off screen.
We learn a little more about Zenitsu and his abilities during the Drum House Arc. It’s during this arc that Zenitsu says every living being, whether it be an animal or person, emits a unique sound that he can pick up on. Once Zenitsu is able to focus more clearly on Inosuke, he remembers him and his performance during the exam.
So that’s the answer. It’s not that Inosuke wasn’t at the final selection, he just finished the exam so quickly that other demon slayers didn’t take notice of him. No screen time was shown for Inosuke during the exam, and he made his entrance within the following arc.