The Rising of the Shield Hero is one of the most intriguing isekai anime currently out there. While it might fall victim to the trappings of a standard isekai every now and then, the idea of a story in which the summoned hero is not treated with reverence and respect, but rather, disdain and disgust, is an interesting one.
But that's not the only way Shield Hero moves away from standard isekai. Naofumi and the rest of the Cardinal Heroes aren't the only ones summoned to this world for a specific reason. There are other heroes here -- however, they are not out to save this world, but rather their own.
Glass' World, Explained
Glass, L'arc Berg, and Therese Alexanderite are heroes from a completely different world. Though they are definitely heroes of their own land, they are antagonists of Shield Hero's unnamed world, out to stop Naofumi and the others from achieving their goal. While this may seem like an awful thing to do to a world already on the brink of ruin, these otherworldly beings have good reason to try and stop Naofumi.
Glass' world is the product of several fights with the Waves of Calamity, the same phenomenon that threatens Naofumi's world. The light novel series reveals that when two worlds attempt to fuse, the Waves are summoned, and monsters pour out until the calamity ends. The weaker of the two worlds are completely destroyed, leaving nothing but a barren wasteland completely incapable of supporting life.
As it turns out, Glass' world and Naofumi's world are attempting to fuse, with the former quickly becoming the weaker of the two. While it is possible to repel the Waves completely and prevent both worlds from being destroyed, the odds of such a thing happening are so unlikely that Glass and the others consider it a wasted effort to try. As such, they believe their only option is to stop Naofumi from fighting back the waves so his world will be weakened instead -- and their world can survive the fusion.
How The Vassal Heroes Do Business
Coming from a world much different than the one we're used to following, the Vassal Heroes (as they are officially known in their homeworld) work in different ways than the Cardinal Heroes. From new fighting techniques to new weapons to entirely unheard of races, the Vassal Heroes have little in common with the Cardinal Heroes, who are simply chosen by weapons and have to make do with what they have.
While Glass may appear to be a normal, extremely powerful woman, she's actually part of a race of spirit people. She uses something called Spirit Power to boost not only her attacks but her stats as well. The more Spirit Power she has, the higher her Attack and Defense rises. When she has enough, she can expend it for powerful attacks using the pair of hand fans she was given as the Vassal of the Fan. This comes with a downside, of course -- expending Spirit Power means she lowers her own stats in exchange for powerful attacks.
In a similar vein, Therese Alexanderite is part of a race known as "Jewels." Born with a gemstone embedded somewhere on their body (Therese's is on her forehead, which she usually hides with a headband), Jewels can harness power from various gemstones and use that power to cast powerful spells. The type of spell a Jewel can use depends on what kind of gemstone they resonate with when trying to cast magic.
The Vassal Heroes are Reluctant Antagonists
Despite being presented as antagonists once their goals are made clear, the Vassal Heroes are not out to destroy Naofumi's world just for the sake of it. If they had a choice in the matter, they wouldn't be attacking another world at all. But due to circumstances out of their control, they've been forced to choose between their world or Naofumi's. While they definitely feel bad about attacking a world that's just trying to survive, their own world is doing the same, and if they can help buy their home another day of survival, then they'll do whatever it takes.
Shield Hero's second season is due to air in October 2021, and it's sure to come with more conflict between the Cardinal Heroes (Naofumi especially) and the Vassal Heroes as they both fight to save their own worlds -- even if it means coming to blows with each other for the sake of survival.
