WARNING: the following contains spoilers for My Hero Academia #324, by Kohei Horikoshi, Caleb Cook and John Hunt, available now in English from Viz Media.
Previously in My Hero Academia, Izuku Midoriya struggled to defeat All For One and the army of villains all by himself until his fellow classmates confronted him and convinced him to rejoin them as loyal friends. Izuku cannot win this fight alone; he never could. He returned to the U.A. school's campus, where an angry crowd of civilians awaited him.
The crowd rejects Izuku, claiming that he will draw powerful villains to the school and put civilians in danger. Ochaco Uraraka gives a heartfelt speech to the crowd, and Kota Izumi breaks free of the crowd to comfort his idol. Izuku is his hero, and Kota represents how far Izuku has come as a true symbol of peace.
The crowds listen skeptically as Ochaco gives her speech defending Izuku and his right to rest at the U.A. school, and these words inspire Kota Izumi to run forth and comfort the agonized Izuku as a loyal friend. This is a risky move for a child in a volatile situation like this, but Kota doesn't care. He is a believer in heroes, an inspired boy who trusts pro heroes to save the day even when all seems lost. Izuku once shielded Kota when the boy was vulnerable, and Kota now returns the favor when Izuku is in his direst moment of need.
This move reflects not only on Kota, but also on Izuku, who has succeeded in becoming the symbol of peace for a civilian: Kota. The #1 hero must inspire the people, not just protect them, and Izuku's defense of Kota against Muscular of the League of Villains changed Kota's heart for the better. Izuku has become to Kota what All Might once was to Izuku, inheriting the symbolic and inspiring will of All Might in full. It's conceivable that Kota will address the crowd in Izuku's defense next, creating a snowball effect where everyone else embraces Izuku as their hero as well.
Izuku's power levels increase rapidly during the story of My Hero Academia, and this incident with Kota Izumi proves that Izuku's symbolic power has likewise come a long way. It's easy for Izuku to inspire his classmates since they have a lot in common with him as trainee heroes -- most of all, Ochaco Uraraka. Izuku even convinced Shoto Todoroki to embrace his power and face his destiny during the U.A. sports festival. However, winning over the hearts of skeptical civilians is an entirely different challenge, and until now, Izuku has done little to inspire the masses.
Izuku has broken new ground by winning over Kota like this, and Kota even got large red shoes to emulate Izuku and prove his loyalty. That's similar to Izuku buying and wearing All Might T-shirts or costumes as a child, and shows that Izuku has already passed on the "you can be a hero" torch to Kota -- the same one he received from All Might. It's too soon for Izuku to retire or quit like All Might, but he is planting the seeds for the next generation -- something that only the true symbol of peace can do.