Post-Post-Apocalyptic Deliveryman

Civilization collapsed due to the proliferation of quadrillions of mailboxes. Today, the most popular jobs in the world are Deliveryman (Sagawar) and Remover (Yupacker).
I work as a deliveryman. I search for food and water that are rarely found inside mailboxes and sell them off. By the way, the Removers just rip the mailboxes out entirely.

This place was once called the Sahara Desert. Now, instead of sand, mailboxes stand densely packed together.
I check the mailboxes one by one, and if I hit the jackpot, I load it onto my Super Cub. Since Cubs also multiply, they have become the vehicle of choice for everyone in the world.
Just then, a shadow fell over me, and I instinctively used a mailbox as a shield.
With a buzzing sound, a delivery drone (carnivorous type) arrived. This is bad; my Sig-Sagawar doesn't have enough firepower. They indiscriminately attack anyone not wearing a postal service badge. In other words, all of humanity.
The next moment, when I realized a parcel locker (carnivorous type) was lurking behind me where I was hiding, I was already screaming and firing away!

"Please provide your seal!"

[To be continued]