So it's understandable that the production went with the approach of giving us a glimpse into the other series through the eyes of the Hero Club, and retell the second half of the second season with more detail. While some moments from the prequel series are featured, it's rather clear that much of the new content centers around Mebuki and her team of Sentinels. We get to see some important moments in the inner workings of Taisha that led to the decisions made by absent adults in the first 2 seasons, and we get to know Mebuki's friends and her rivalry with Karin that predated the Hero Club.
And yet, whether because of time constraints or a desire to hold off, the prequel content featuring Wakaba was distilled down to a series of flashbacks, giving us little time to get to know half the team before they're cut down by the Vertex. We do see the primary conflict of the series between Chikage and Wakaba, but this is enough to spoil all the drama without animating the full 13 episodes. Perhaps it could be argued that the gritty realism might have been a bit much even for a Yuusha series known for extreme emotional drama and graphic non-sexual violence against young girls, but it might be better said that this is an introduction to the broader canon, beckoning the viewer to explore the stories of the other teams in the light novels and manga.
The all-new content centers on the Hero Club after season 1, giving us the charm that attracted viewers in previous seasons (with an additional layer of weird due to Sonoko stealing the show), and episode 1 features several songs released on a companion single. The final episode includes an epilogue for the YuYuYu time period, signifying that there probably will be no new content in Yuuna's story on the screen. It's a good ending, depicting how the girls have moved forward years after the final mankai.
Visually, it's on par with the first season, however there were a number of moments where the lighting/color grading seemed unnecessarily dark (some of the action cuts in the opening credits, for example). Speaking of opening titles, this animation sequence evolves as more of the canon is introduced, and the "releasing" vines towards the beginning is a really nice touch. The opening and ending songs are easily the strongest in the series. The soundtrack expands on the excellent soundtracks of previous seasons, culminating in a new track for the reprised climax from season 2. I think I prefer the original, but the new music was also quite strong.
