Where are Haruka, Michiru, and Hotaru in Crystal Tokyo?

[Ryuondo]

They chill in their little recon castles out in the outer solar system. They prevent invasion from outside the main Queendom. A border guard so to speak. I'm pretty sure that's where they said they were in the manga.  

[l Sailor Cancer l]

These were all their castle names and posts they were stationed at. all the names are based on a moon from that planet these names are also in the manga and sourcebook.
Uranus's was called Miranda
Neptune's was Triton
Pluto's was Charon /the time door
Saturn's was Titan
Venus's was Magellan
Jupiter's was Io
Mar's was Phobos Deimos which were also sailor senshi and rei's crows
Mercury's was Mariner