So, another Shield Hero AU with a different shielder. Again, some might be sick of them already… SO! Here is my idea:

Our main hero, the future shield hero, Cain Weslow is a soldier, a general to be exact. His country, Reimer, is one of the last strongholds of humanity left on Earth. Some 400 years ago, the year 1893, something VERY wrong happened when a scientist tested a new weapon but it made the insects grow large and aggressive. Ants are the size of German shepherds and beetles can be as heavy as a jeep, if not bigger. The bugs are unaffected by bullets and most conventional weapons due to their hard armored shells, so the only way to kill them is usually by using a modified piercing gun to puncture through their shells, use blunt force to crush them or make a big enough explosion to blow them. This means that the most used weapons are said piercing guns, warhammers, mallets and many such, including, as some may have guessed shields that can be used to protect against the bugs' mandibles and to slam them with enough force to be killed. Also, due to their way of living and change of diet due to lack of a LOT of animals, humans in that world are much stronger than average.

Cain is famous as the Demonic General for several reasons- he has never lost a single fight against the swarms of bugs, his presence alone has turned the fight in humanity's favor many times, he wears a spiky armor that can look quite scary when covered in insect blood and his signature weapon is a large shield. The large shield was made from the head of Carrothos – a giant 'war beetle' that had terrorized a trading route for a while but no one had managed to defeat it. Cain had led his army, the battle had been fierce but he alone, with only a piercer shield (medium-sized shield with a single stinger-like spike in the center) had managed to deliver the finishing blow. As a sign of gratitude for defeating the beetle, he was gifted a shield made from the monstrous bug's head. The shield was tough and lightweight despite its size, the bug's face instilling terror in all enemies.

Cain had returned home for a break after fighting off a swarm of wasps wanting to create a nest near a mountainside village. He had been talking with his sister, a librarian, when the book of Four Cardinal Heroes dropped on his head. He opened it out of curiosity but got summoned, right in front of his sister's terrified eyes.

In Melromark he is the Shield hero, like in canon, they don't like him but he just scoffs at the other 3 heroes when they tell him the shield is useless. Arrows, swords and spears DID NOT work as viable weapons in his world at all. They were mostly used as decoration to remember the 'old times', plus, no one had seen him defeat a car-sized scorpion with only a shield and armor. He heads off alone to try and find a way home while fighting off the Waves.