Some TMNT stuff was always meant for grownups.
Lucindra Thompkins is a human female martial artist who befriends and spars with Raphael. She is one of the few human characters in the series that is uniformly a better fighter than any of the Turtles.
Lucindra first appears in the short story The Name is Lucindra . Raphael calls her up for a sparring session, and since she isn't too taken aback that he's a giant Ninja Turtle, the two proceed with their kumite. Raphael loses to Lucindra (two falls out of three) and thus he owes her a Pizza.
She returns in The Violent Underground, where it is mentioned that she has been sparring with Raph for some time at that point. After thrashing Raphael once again, she heads home, failing to notice a Foot Ninja that is tailing her. After encountering a number of people, including a drug dealer who emphasizes that her brother Malcolm needs to pay his dues, she finally makes in into her apartment. The drug dealer is killed by The Foot shortly thereafter.
- Lucindra's first name is a blend of the names Lucille and Sandra. Lucindra explained that her parents couldn't choose between the two.
- Although Rick Arthur's TMNT stories were done as work-for-hire, he retains the rights to the character of Lucindra.   
- The colorized reprints by IDW Publishing of the issues Lucindra appeared, in gave her a lighter skin tone resembling caucasian. In general, the IDW colorized reprints were largely outsourced to outside firms and could be wildly inconsistent with color palettes, sometimes inexplicably changing from issue to issue or even contradicting palettes used by a same issue's original Mirage cover art.