From Infinity Studios:
Having been born in a secret government laboratory that cultivated esper (telepathic) powers within humans, Shuuichi and two sisters, Sumire and Katsumi, are forced to endure a difficult life as test subjects until their escape. Years later, these siblings are still being sought after by unknown organizations that are after Shuuichi's powers as he is what they refer to as the “zero-sample” with the ability to cause “zero-shock.”