Returning to the Phantom Color World

What made the best fuel?

High efficiency? Cleanliness? Or renewability?

Today, for the first time, Thor had seen someone use wizards as fuel.

"City Lord Ophelia, although you're a Tier 4 Wizard, aren't you afraid of backlash from refining the corpses of Official Wizards into fuel?"

Thor's tone was fairly calm. He wasn't speaking with righteous indignation.

"You misunderstand, Wizard Thor. I didn't kill these people. They died in various accidents. All I did was process them a little and put them to use as waste."

Ophelia's voice still came from overhead. She still hadn't appeared.

Thor thought of what he'd seen the first time he came to Sky City.

"The corpses that disappeared along the way—were they brought here by the Whisper Flowers? What is this place?"

"A bunch of people who aren't worth bringing back to life. Why should they care what happens to their corpses?"

Thor fell silent for a moment.

Corpses disappearing had become an accepted rule in Sky City.

But those people probably never imagined what their bodies would eventually become.

"If you have no other questions, we can begin the third connection experiment now."

Thor shrugged. "Then I'll trouble you to activate the core, City Lord."

He had a rough idea of what this place was.

This enormous Fuel Furnace was probably the lower half of Sky City, wrapped in clouds.

Ophelia had said this was the core of the Mechanical Heart, but there had to be more to it than that.

The energy radiating from the entire Fuel Furnace was immensely powerful. It was probably what kept Sky City flying.

To improve the experiment's chances of success, she had brought Thor to the core of Sky City. That showed considerable sincerity.

Following the steps of the previous experiments, Thor began setting up the