Within the river country, an old laboratory laid hidden in a cave. In this Laboratory, Orochimaru, one of the three legendary Sannin from the hidden leaf village, and lord of the hidden sound village, did experiments on five pregnant women. By using forbidden jutsus and rituals, the sound lord was able to summon demons from other dimensions, and use their energy to empower unborn babies. His goal was to turn them into mindless creatures that will strengthen his village's power. His experiment failed.

The babies looked normal. So, Orochimaru called it a failed experiment and slaughtered the women and abandoned the babies in the laboratory to die. One year passed, and the sound lord returned to the abandoned laboratory to retrieve some documents he had left. But when he arrived, four babies' corpses were missing, and the fifth was surrounded by a pact of dead wolves with bite marks around it. To his surprise, the baby was covered in blood, dirt, and dust, but well alive. The baby had a unique, mysterious marking around his right eye. So the sound lord decided to raise the child as a ninja.

Twelve years has passed since the experiment failed. The infant, who is now a pre-teen, has become Orochimaru's secret apprentice, with only three other shinobi knowing of this; Kimimaro Kaguya, Kabuto Yakushi, and Suruya Gimoichi, a medical ninja that is forced to work for the sound. This is the story of a demon ninja's life in the corrupt world of shinobi. This is a story of demon shinobi-Mezuki.