Transmigration

In an underground cave, we see two men wearing priest-like outfits, long white hair, and odd tattoos.

"Another failure," one of the priests replied with anger as he threw away a dead child.

"How many times now? We need a new blood user. Give me another child now!" he exploded with anger.

"Yes, sir," the second priest replied, wasting no time.

The second priest arrived at a jail cell filled with about 40 children, crying, shivering, begging in their minds not to be chosen next.

The priest looked around, darting his eyes across the children. Eventually, his eyes fixated on a certain young boy in the dark corner of the room.

"You, come here now," he demanded.

The boy walked forward into the light, his features now being shown.

The boy stood around 3ft 6', had dark black pupils, messy black hair, and fair pale skin. His expression looked like he was about to break down into tears at any second.

After dragging him into the main cave section, both priests looked at each other, nodded, and threw him into the middle of the ground where a large symbol of a circle with an upside-down triangle was drawn on the floor with candles surrounding it.

"We will start the ritual. Bring the sacrifices," the first priest said with his eyes closed while the other priest gathered ten knocked-out children and laid them around the boy.

"Oh Lord Jashin, hear our prayer. We bring ten lambs for you. Bless this vile boy and bring him into your ranks, Lord Jashin. We pray to you."

All the blood inside the other children left their bodies as they shriveled up, and the blood traveled into the boy in the middle.

He began having a seizure as the blood inside his body went out of control. Blood started entering and leaving him, and he let out bloodcurdling screams.

"AGRRRRHHHHH, PLEASE STOP, STOP!"

This went on for an hour, and just when the priests thought they could succeed, the boy died.

"No, no, no, NO, NO, WHY, WHY? What are we doing wrong, brother?"

"I don't kn—" Before the second priest could reply, the entrance to the cave exploded.

A ninja with a mask resembling a dog's face, with red and black markings on the side and grey spiky hair, ran through the cave.

"SHIT, BURN THE EVIDENCE NOW! WE CAN'T LET THEM LEARN ABOUT LORD JASHIN!"

The second priest did a few hand signs, and the cave containing the children exploded with the help of fuinjutsu, killing every last one.

Except, all of a sudden, the boy who had the ritual done on him shot up, gasping for air.

"Where am-.'' Before he could finish his sentence he passed out again.