The Infinite Chain Of Death

After the energy reading, they began to check Akuma's skills. 

"Listen kid, while I said you could make S rank, that's if you have the right skills", the captain didn't want Akuma to be even more disappointed. He did still want to recruit him after all. 

Akuma simply nodded, and they took the reading. 

"First, we'll look at your acquired skills", the captain had decided. 

"Sealing fist - Is that the one you used on me?", he asked and Akuma nodded, "What's this? Kuro field skill. So, your family has a battlefield skill too? What's this? A second sealing skill - Shadow cage."

The captain was already impressed. 

"Lets look at the innate ones now."

He had clearly piqued their interest, but this was the important bit. They were about to find it. 

"Only one?" The captain teased him. "Wandering sp- oh no."

The captain found it.

"There's no hope", one of the guards observed.

"Sorry kid", another commented.

"The curse."

They had all heard of the skill - Wandering spirit. The hereditary skill of the Kuro clan, and the main reason for their downfall. 

There was a reason for its nickname - The infinite chain of death. It was said that, upon its first activation, it guaranteed the death of every being in the universe. 

The chain could be slowed, but never stopped.

It was a passive skill, triggered when the bearer killed any animal. 

The being's soul would be violently ripped from its corpse and be unable to rest until it killed another being, and its victim would face the same fate.

A perpetual motion machine; the cycle would continue forever, until only one being remained, forced to wander the empty world eternally. 

With anything being reduced to a tamed beast, forced to follow its master under partial control, until it can find another being to pass its fate onto, with its only desire being to kill.

It was due to the skill's cruel and uncontrollable nature that the Kuro clan was forced to adopt pacifism, literally unable to hurt a fly.

"We did want you to join the royal guard", Akuma felt the rejection coming. "They'll never take you with that skill, not even as a teacher or advisor." The captain was just as disappointed as Akuma.

"Surely they could make an exception", he found himself just as disappointed as them. He needed the training and money that only they could offer. 

"Please?", Akuma made it a habit not to beg, but at this moment, found himself forced to. 

"Sorry, no exceptions. Even the caster can't control the soul's urges to kill, otherwise your clan would still be one of the strongest."

"Please", Asaka begged for her cousin. It was obvious how much he wanted the position. 

"Well", one of the guards reasoned. "He does have sealing skills."

"Pretty good ones at that", a second added.

"Hmmm", the captain though carefully. "Fine, I'll recommend you to the official evaluation, as long as you'll join my unit."

"Okay", Akuma replied, relieved.

"You can take your cousin to watch the evaluation, or anyone else you want. Are you guys done collection taxes?" The captain wasted no time sorting everything out. Akuma was talent he couldn't afford to miss.