My Hero Academia explained the power of Izuku Midoriya's newest quirk, Fa Jin, with the newest chapter of the series! The Final Act of Kohei Horikoshi's original manga series is now in full swing as Izuku is currently in the midst of his first real effort against someone sent directly by All For One. While it's not his first fight since unlocking all of the remaining abilities within One For All, this fight against Lady Nagant has seen him put his new quirks to the test as they become all the more necessary to survive.
A previous cliffhanger of the series officially debuted the quirk that once belonged to the third One For All host, Fa Jin, and it was revealed to be a technique that allowed him to rocket propel himself fast enough to quickly close the distance between he and Lady Nagant. As their fight continues with the newest chapter of the series, the series has now fully explained what Fa Jin actually does as it becomes a crucial part of Izuku's arsenal.
Chapter 315 of the series continues the fight against Lady Nagant as Izuku seemingly failed to get through to her and convince her to stop working for All For One. Needing to move much faster as Nagant put Overhaul in her crosshairs at the end of the previous chapter, he has to use Fa Jin in tandem with his Blackwhip quirk. It's here that we get a full explanation of what Fa Jin actually does as it stores and explodes with energy for those boosts in speed.
As the series explains, Fa Jin uses repeated movements to build-up motion based energy for temporary storage and usage. So it builds kinetic energy through smaller moments and stacks it until he decides to use it. The example Izuku shows us is how he has been flexing and extending his legs to protect himself from Nagant's attacks while building up energy to use when he really needed it. It's why he had to brace himself when he used it the first time.
It's revealed that Fa Jin gives him the speed boost he needs while only needing to expend one leg's worth of built up energy at a time, and now he'll soon begin using it together with the other One For All quirks to help him on the road of mastery. With each one much stronger than they had been in the past, Izuku's going to have to catch up quick before he's face to face with All For One. But what do you think of the power of Izuku's newest quirk, Fa Jin? Let us know your thoughts in the comments or you can even reach out to me directly about all things animated and other cool stuff @Valdezology on Twitter!