Honestly I really love this series. The feelings are deep and strong, and they're worded so intensely. I also love the balance of NSFW with story. Real life has NSFW aspects (more often than shown in most fiction). It makes the story seem so much more real to me.
Personally the two others, Etsuko and Tomomi, are also decent characters in their limited capacity. I would've liked to see them flesh out a bit more and maybe given a companion arc that puts them together and explains more of how close Kanae is with Tomomi.
While some have pointed that Chizuru's behavior is somewhat disturbing, but I actually think it's pretty decent. She only buys things her crush, Kanae, has to feel closer to her. She doesn't stalk her or invade her life like the Stalker With A Crush trope usually does.