I'm a Mechanic in Hell

In this world, machines are everywhere, and engineers have become a profession. They can grow stronger quickly and enjoy a status above that of ordinary people.

But to become an engineer, you must pass the mechanical aptitude exam, fuse with a mech spirit, open a mechanical space, and acquire a mechanical core. Complete all that, and you’ll become a great engineer.

“Why doesn’t your mech spirit space have a mechanical core?”

“Huh? What would I need one of those for?”

“How can you build machines and grow stronger without a mechanical core?”

“Oh! I grow stronger by devouring other mech spirits!”