A Wage Earner Is Transported to the Zombie World

In a world where zombies are rampant, the sky suddenly changes, and with a loud cry, a cylindrical protective warehouse falls on the roof of a building. This is a cool novel about a wage earner who is transported to the zombie world. The content is full of twists and turns. How about an upgrade to fight monsters? It doesn't exist. The protagonist, a wage earner, is a low-level person, but he turns around in the zombie world and becomes a superior person. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.