Rather than fucked up, Mai-chan is just shock content. There's like 200 pages to develop the characters and make the audience care for them before brutally destroying them, yet only 20-25% was spent on that. If you want something actually fucked up, I recommend "
Loli tomodachi" and it's prequel by Quzilax, which not only is more fucked up (most of his works also fit the bill), but it also has one of the best stories of the thousands of doujinshi I've read, featuring morally grey believable characters, their descent and their friendship. It's even been praised by Hanazawa Kengo who did "
I am a hero". Another noteworthy mention goes to anything by Shirukabakaudon/Chemical Janky, specifically "
Kimi ni aisarete itakatta" as it's an actual serialized manga with a plot rather than just senseless rape/gore for shock value.