Most of Volume 8 wraps up the Deathbusters arc. Hotaru's body has been taken over by Mistress 9 who starts to awaken Master Pharaoh 90 to take over the planet. Chibi-Usa and the Inner Scouts are incapacitated. It's not looking too good.
Hotaru does manage to fight off Mistress 9 and restore the other scouts and with the help of Super Sailor Moon, is awakened as Sailor Saturn, the Guardian of Silence and protector of Saturn, the planet of ruin. Sailor Saturn also has my favorite character design:
(spoiler show)
If there is a competition for who is the most powerful guardian, Sailor Saturn would definitely be a contender due to her ability to destroy worlds. As a result, she isn't awoken often. She even comments:
"It seems I will forever remain the uninvited guest, hm?"
Saturn does also point out that she serves as the Guardian of destruction and death, only to bring about rebirth. After redirecting her powers to stop the oncoming destruction and save Earth, she knows that it will also lead to her death. Super Sailor Moon does manage to tap into some of her powers and help bring about the rebirth of Hotaru, who is taken away to be raised by the outer scouts.
The last chapter starts off the fourth arc, the Dead Moon Circus which arrives during a rare total solar eclipse. For whatever reason, even though this season was broadcast in the US, I at most only saw a few parts of it. I know a few details, but otherwise am going into this blind. I'm excited and have enjoyed what I read so far.
Also, in case you do like Sailor Moon and haven't heard, they just started airing a remake of the series which can be seen worldwide and will air one episode every 1st and 3rd Saturday a month. The first episode, which follows the first chapter of the manga, premired July 5th and is free to watch on the websites niconico, crunchyroll, and hulu. I'm not sold on the new transformation, but I love the opening and art style. It looks like they'll be sticking straight to the manga and the 26 episodes we've been promised will take us until the end of the second arc of the manga.