Old School Cursed: The Magic of Gu

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the name of the comic is Kengan Ashura?

Gu (simplified Chinese: 蛊) or Jinchan (simplified Chinese: 金蚕; "gold silkworm") was a venom-based poison associated with cultures of south China, particularly Nanyue.
In Chinese folklore was developed a whole literature on the magic of harm, sicken or eliminate people somehow perceived as antagonistic. The preparation of Gu potions involved the used of the posion of several creatures (sneakes, centipedes, scorpions), sealing them inside a closed containter where they kill and devoured on another.
The only survivor would have accumulated all toxic substances of the losers. 
Gu magic was used to manipulated the will of others, partners, to make people ill and not lease cause death.

The Process of Making Gu, “It said Zhuang women go to a mountain stream and spread new clothes on the ground, with a bowl of water beside them. The women dance and sing naked, inviting a visit from the King of Medicine (a tutelary spirit). They wait until snakes, and poisonous insects come to bahte in the bowl. They pour the water out in a shadowy, dark place. Then they gather the fungus which grows there, which they make into a paste. The put this into goose-feather tubes and hide them in their hair. The heat of their bodies causes worms to generate, which resemble newly-hatched silk-worms. Thus Gu is Produced.

However, accourding to the zhouli commentary of Zheng Xuan “those who dare to poison people with Gu or teach others to do it will be publicly executed”. One story tells of the daughter of Empress Chen Jiao (unable to have children) who had beed accused of practicing Wugu and Maigu through the use of a fetish positioned close to the unconscious victim. The empress was removed and more than 300 people involved in the case were sentenced to death.