Satou is a manga editor who suffers from ‘Magical Girl Phobia’ triggered by dreams featuring a mysterious magical girl. However, one day, he comes across a manga featuring illustrations strikingly similar to the magical girl from his dreams. Determined to uncover the cause of his phobia, he contacts the manga's author. But this marks the beginning of a descent into a dark, profound despair.
The manga centers around Ginjirou Manda, a loan shark business man who is affiliated with many Yakuza gangs in Osaka. He charges an interest rate called toichi—10% more interest every 10 days, or 365% every year. Thanks to his unrelenting money-collecting tactics, he is feared as "Minami no Oni" or the "Demon" of Osaka's Minami business district. Even when his borrowers tries to scam him, he always finds a way to make them pay his money back.