So Infinite Stratos shows it's colors in this one. It is what it is, a romance harem based series where we focus on a different girl or two and their attachment to Ichika each volume. Don't expect the greatest plot in the world. There's no real "enemy" or "goal" (besides graduating and finding "someone worth protecting" for Orimura).
About the most major "story" element, if you can call it that, introduced in this one was the sort of international students spying on other IS tech. Charles, the "male" character of the volume makes no bones about his spying on Ichika's wep. Same for our German counterpart, Laura. They talked about how protecting the IS pilots is almost a secondary concern to protecting the IS themselves.
We learn more about Chifuyu through some of the other characters, particularly Laura and Houki's sister. The biggest thing being that she sees her brother as strong.
On the explicitness of the series, this one really did increase that element. The main character is going through puberty, so I understand it a bit, but the author is putting him in really awkward scenarios. The "falling down on top of another character trope"... Was it new when this released? It's just so tired. I'm curious where they're going with the romance. I know many fans like Charles, so it'll be interesting to see who the author ends up favoring at the end. Houki's relationship doesn't seem healthy, mentally straining for her; I hope she moves on. Maya would be a bit too age gapish, creepy. Rin would be ok, but she is a bit rash in terms of abuse and I hear not a huge fan favorite. Cecilia and Laura seem like the most normal of the crushes so far, but I guess we'll see.
The ending for the volume was something. Like, so far Orimura has mostly only suffered CTE from their abuse from jealousy, but now they're trying to kill him. Like, yikes. It's the kind of ending that only works if you think of this as a Cartoon. xD