This predaton method is just kodoku isnt it!? instead venomous thing, yayoi change it to ghost @_@
You're correct. Gu is the term in Chinese and Kodoku is in Japanese. Both are essentially the same thing.
Gu sorcery, also known as gu poison, is a venom-based poison associated with cultures of south China, particularly Nanyue. The traditional preparation of gu poison involved sealing several venomous creatures, such as centipedes, snakes, and scorpions, inside a closed container, where they would devour one another until only one survivor remained. The fluids of the last surviving creature were then used to create the poison.
This is the base of graduate-production system. Only this time in the flashback, Yayoi used a group of Shinigami instead of usual bunch of vengeful ghosts.