Lady Nagant appears in current 2nd part of 6th season
The official website for the My Hero Academia anime confirmed on Saturday that Atsumi Tanezaki voices Lady Nagant (a former top-class hero who was imprisoned Tartarus before escaping) in the second cours (quarter of the year) of the sixth season:

The anime’s sixth season premiered on October 1. The season will air for two continuous cours for a total of 25 episodes. Crunchyroll is streaming the anime as it airs in Japan, and it is also streaming an English dub. Toonami is airing the anime.
Eve is performing the new opening theme song “Bokura no” (Our), and the three-member rock band Six Lounge is performing the new ending theme song “Kita Kaze” (North Wind).
The new season has so far adapted the “Paranormal Liberation War” arc of Kōhei Horikoshi‘s original manga, which features an all-out war between heroes…