WARNING: The following contains spoilers from My Hero Academia Season 5, Episode 13 "Have a Merry Christmas!" now streaming on Funimation, Hulu, and Crunchyroll.
Now that the drama from the Joint Training arc is dying down, My Hero Academia checks back in on Deku and his progress with One For All. As Mt. Lady instructs a hero PR training course, she asks the students to show off some ultimate moves. Flashy techniques with catchy names are essential when it comes to building a hero's brand. Once Deku's nervous system comes back online following his disastrous fake interview, he decides to show off his new Quirk, Blackwhip.
In a sequence that is quintessential Izuku Midoriya, he musters all his strength and concentration to conjure the tiniest wisp of his new Quirk, to his utter delight. While everyone around him collectively sighs, eye-rolls and facepalms, Deku is as determined as ever. He isn't embarrassed in the slightest by their reactions, showing just how important mastering this new power is to the aspiring hero.
While Blackwhip would be far from his ultimate move, choosing to try it out when prompted to show off is very on-brand. He's not interested in showboating -- rather, he sees this as an opportunity to improve. Deku would certainly practice much more often if he weren't constantly being interrupted by sleep and school. He understands he must always be pushing his limits if he ever wants to master One For All and become the #1 Pro Hero.
Deku knows that if he can control a tiny amount of Blackwhip's power, one day he will be able to control it completely. Give him an inch and he'll take everything, because the slightest chance is all he has ever needed in My Hero Academia. It is an important distinction that he is proud, but not satisfied with his minimal success.
After all, Deku knows the only path to success is forward. The fact that he's willing to use Blackwhip around so many people so soon is both a testament to his work ethic and an interesting gamble. It adds to his resolve to master it because if he loses control, he could hurt the many people around him. However, this time there is more than enough firepower present to stop him, and his classmates wouldn't be caught so off guard.
Despite vowing to not attempt to wield this power for a long time, it makes sense that once the shock of this latest revelation wore off, he would give it another try. Deku is practical enough to recognize that it is truly a gift to be able to wield multiple Quirks in My Hero Academia. It would be a waste and a shame to not utilize this power out of fear.
Deku's control over this comically small amount of power is the first step to redeeming himself after burdening his teammates during their Joint Training match. Now that Tomura Shigaraki appears to be on the move, and crazier than ever, the clock is ticking whether Deku knows it or not. It's only a matter of time before he will find himself in need of Blackwhip's incredible power.
