Chibi Usa’s sickly friend Hotaru isn’t just Sailor Saturn, Deity of Destruction. She’s also possessed by Master Pharaoh 90. Facing this cataclysmic power will be impossible–unless Sailor Moon can unite the powers of every Guardian of the Solar System.
Then, when the moon eclipses the sun, a mystical unicorn begs for help. An elaborate ship floats through the sky, and Usagi and Chibi-Usa have trouble seeing eye to eye… (from Goodreads)
This volume is the ending of one arc and the beginning of a new one. There’s no doubt that the senshi beat the evil forces, of course. The outer senshis leave for good, apparently, to raise the reincarnation of Hotaru (Sailor Saturn).
The new arc begins with an eclipse, that obliterates the senshis’ powers and they can’t transform any more. And the whole pegasus story appears, which I never found very interesting when I saw the anime, but let’s see how does it go here.