A brief description of the Master Of Gu manga:
This manga tells the story of Fang Yuan, the villain that magically got into the past for half a century, with the help of ChunQiu, a cicada, which himself grew for a long time. Thanks to his wisdom and great life experience, he wants to defeat his enemies with his sharp mind and skills! Fang Yuan is absolutely ruthless and cunning, pursuing his goals in everything. In a cruel world, where people are constantly improving with the help of magical creatures, Fang Yuan uses only his own strength.
The magical creature is Gu, an insect that is often used in black magic rituals. It easily takes the form of an insect or snake, cricket, worm, etc.