The following content will contain spoilers from My Hero Academia Season 6, episode 20 (currently streaming on Crunchyroll), but refrain from divulging too much manga-only information regarding Lady Nagant's past. The mysterious Lady Nagant has been teasing viewers about her big debut since the second cours of My Hero Academia, Season 6 featured her iconic hair in its OP, and her time to shine has finally arrived. Unfortunately, her grand entrance is not a cause for celebration, as she introduces herself as Deku's main opposition, in lieu of the League of Villains' familiar faces.
Lady Nagant (who shares Anya Forger's voice actress) finally manages to track down Deku in Season 6, episode 20, with a new Quirk in tow and Overhaul surprisingly still by her side. She has evidently not acted impulsively with her strategy to incapacitate the enemy, ensuring to target Deku's communication and tracking device first, isolating him from the Pro-Heroes' support. It is suggested that she also has something to do with bombing the Heroes' vehicles, although it is unclear exactly who is behind that assault. Either way, Izuku has been forewarned about Lady Nagant's incredible capabilities, but it appears that those wise words have fallen on deaf ears.
Lady Nagant's "Heroic" History
During her prime, Lady Nagant, born as Kaina Tsutsumi, worked at the Hero Public Safety Commission as Hawks' superior, and much like the winged wonder, she began training as a spy from a very young age. Taking full advantage of her Quirk, Kaina was turned into an efficient assassin with a sky-high kill rate, which eventually began wearing away at her conscience. Leading a double life as a celebrated Pro-Hero and a cold-blooded killer became too much to bear, particularly when she was instructed to dispose of a couple of Heroes one day. Her spiraling situation eventually leads her to the gates of Tartarus, after sadly losing faith in the world and acknowledging that corruption knows no bounds.
The Human Sniper Rifle
Lady Nagant is renowned for being the best marksman in Japan, if not the world, who has never allowed a victim to escape her line of fire (until Deku came along, that is.) Even Snipe's foolproof Homing Quirk, with its convenient target selection and 600m range, is no match against Lady Nagant, who can successfully aim from three kilometers away (or 1,609 miles) with just technique alone!
Technically speaking, Lady Nagant's Quirk, Rifle, only influences two aspects: the ammunition and the weapon. Kaina's pink-and-purple hair gets plucked from her head and transitions from malleable to rock-hard, allowing her to create various types and shapes of bullets, whereas her arm can fold over to reveal a sniper rifle (in a Tarantino Planet Terror kind of way.) If needed, this gun can change size and form to add power to her "punches," and she is capable of firing multiple shots in quick succession, giving her enemy little chance to recover. Lady Nagant can also create and mount a scope for added accuracy, but even then, hitting the mark is not assured. Although it seems like Kaina can bend bullets, Rifle has no control over their trajectory; pure skill is what makes her aim ring true.
Furthermore, her newfound Air Walk capabilities work in a similar manner to One For All's Float, which levels the playing field ever so slightly. When combined with her specialized skillset, Lady Nagant's added maneuverability allows her to obtain the perfect placements to shoot from or allow for swift repositioning if any last-minute changes crop up. She seems to prefer working as a long-ranged sniper instead of closing the gap between herself and her prey; likely due to her many years of working from the shadows as a hit-man for the government.
Lady Nagant Becomes All For One's Ally
Amidst the turmoil of Tartarus, Lady Nagant is approached by All For One and boldly questions the supervillain, without a hint of fear in her voice. Her confidence is either fueled by the arrogance that accompanies her top-tier Quirk, or a nonchalance regarding her survival or future. Lady Nagant appears to be going through the motions and following the easiest path; although clearly not without compassion. Why else would she drag the babbling Overhaul around with her? All For One didn't cultivate their team up, and the handless villain shows no signs of contributing in any way, shape, or form. As far as viewers can tell, Lady Nagant had no prior knowledge of Overhaul's role as the Yakuza Boss for the Shie Hassaikai, and simply fell back into her Hero habits when she decided to help him out.
In contrast, All For One is evidently aware of Kaina's scandalous past and uses her disdain for the corrupt Hero Society to find commonality with the abrasive woman, ensuring her that the imbalance of power will not falter as long as a certain inspirational Hero is around. After receiving an all-new Air Walk Quirk and agreeing to fight for "freedom," Lady Nagant's current goal is to capture Deku and deliver him to All For One, alive, meaning that she will have to be very strategic when it comes to the trajectory of her bullets. Hawks had already hinted at this possibility, and so the perceptive youngster will assuredly use her need to keep him alive to his advantage. The battle rages on in episode 21 with "The Lovely Lady Nagant," who may be susceptible enough to fall for Deku's charm and retrain her sights toward redemption instead. Only time will tell.