The flashback reveals Iruka’s first days as a teacher. The Third Hokage personally assigned him to be Naruto's teacher—a role Iruka initially accepted with reluctance because Naruto reminded him of his own past pain.
As the village celebrates Naruto for defeating Pain, Iruka reflects on their early relationship.
For more details or to watch the series, you can find the Naruto Shippuden page on Crunchyroll. What happens in Naruto Shippuden episodes 176-196?
This episode provides deeper insight into the Academy days that were only briefly touched upon in the original Naruto series.