If you think the synopsis and the battle royale part sounds close to the Holy Grail War in Fate series, you aren't mistaken. Welcome to the more shonen version of Fate - in the form of a fanservice story. I regret not looking closely at the cover before getting this, because the design itself should have clued me in to how seriously this story is going to take itself.
The basic plot is that mercenaries (mostly) around the world, each as an aspect of a Chinese zodiac animal would take part in a battle royale that has them killing each other for a wish. To up the stakes, each of them has unwittingly ingested a poison crystal, and in a gruesome version of 'capture the flag', the last person standing with the others' crystals wins. Each of the contestants has their own superpower, be it 'making it rain' (despite how awesome unlimited ammunition might sound to some people, I think it is the most ridiculous one), or controlling birds, or raising the dead. They never mention where they get the powers from, or if they get it when they get selected. The backstories for the characters don't serve up much clue either, and things don't match up - if Chicken already had her powers, did Ox also always have her powers or did she get it after killing her sister?
The characters are, well, boring and generic, and none of them stand out as for us to root for. Besides, all of them keep declaring how they kill ("I kill indiscrimately!!!") as if it is part of their title or something - every damn time they meet another contestant, as if they haven't already been introduced to each other FFS. There is one observer character who is overseeing the contestants, but he serves to mostly recite the contestants' stats (what do their height and weight have to do with a superpower match IDEK). I wish he was a bit snarky at least, for the amusement of the readers, because just the costumes alone would be enough to make fun of. The Ox fighter comes dressed like a lady for a battle (with high heels! can we stop that trend PLEASE?!), the Rabbit is like he stepped out of a WWE ring, Rooster's fighter is like someone took a Halloween outfit for Cupid and rolled around in a barn.
The only saving grace (and that is being generous about it) is the artwork layout. It matches well with the battle style of the story, and has an emphasis on cool action scenes with explosive fight tactics. The scope of their powers also comes out well, especially when you think about how they must have used it as mercenaries. But at the core of it, it doesn't feel like it has any substance.
Received an advance reader copy in exchange for a fair review from Viz Media, via Edelweiss.