This is a storyline set 15 years in the future of the Usagi Continuity and it is based around the idea of a Martian invasion. The Martians are the same ones H.G Wells created and their plan is as described in his book the War of the Worlds.
Being set outside traditional canon Sakai gathers as many characters as he can to guest star in this epic volume. He gets to resolve events we never thought we would see yet it does not spoil the current continuity. It also means he can make the invasion a deadly one. Lots of popular named characters die. If this was the last ever volume you would be stunned and heartbroken but as everyone is still alive in the current timeline you aren’t traumatised. This is either the best or worst of both worlds.
Sakai’s re-interpretation of this story is great with the aliens being compared to Tako (Octopi) and the Tripods called Three-Walkers. These fit right in with the period anthropomorphic nature of the Usagi world and everything feels highly integrated – unlike Space Usagi. However there are a few Godzilla inspired moments which give you a great laugh.
It is an excellent hardcover that is a joy to hold and read. There are the wraparound covers from the single issues that show you what a master of composition Sakai is and there is an Usagi/ Stan mini strip that explains the origins of the story. There are also details of some elements that were updated for the collected edition revealing just how much of a perfectionist he is.