As the series progresses, this phrase takes on a heavier tone. It represents the burden of the "Next Generation." To have "the idea" means to understand that the old ways of hero society—relying on a single Pillar of Peace—are over.
When Izuku accepts this, he isn't just picking a cool hero name; he is choosing to view himself through the lens of Ochaco’s optimism rather than Bakugo’s cruelty. It’s a lesson in perspective: our identity is often a reflection of who we allow to define us. Mutual Inspiration
The most immediate significance of this idea is the reclamation of the name "Deku." Originally a slur meant to denote helplessness (meaning "one who can't do anything"), Ochaco flips the script by suggesting it sounds like dekiru ("you can do it").
Ochaco’s ultimate realization is that a hero’s job isn't just to punch villains, but to see the humanity in the people society has discarded. When she stands on the roof of U.A. to defend Izuku to a fearful public, she is executing the ultimate "idea": that heroes and civilians must protect each other. Conclusion