Derrick Rose -- Accuser Consented to Group Sex ... Mad Over Sex Toy

NBA superstar Derrick Rose says he and his friends are NO RAPISTS -- claiming the ex-girlfriend accusing them of drugging and gang raping her is LYING because she gave them consent to have sex on the night in question ... this according to court docs obtained by TMZ Sports.

We broke the story ... Rose's ex sued the Chicago Bulls player claiming Rose and his friends broke into her L.A. apartment in 2013 and gang raped her while she was incapacitated.

Rose has now filed docs of his own in which he claims the accuser "consented to sexual interaction with more than one co-defendant on more than one occasion, consented to sexual interactions on the day in question, and invited the defendants to her apartment and buzzed them in."

Rose says things were so cool the following day -- the accuser casually had a cup of coffee with her roommate in the morning after the sex ... and headed into work for a full shift. The implication is that a rape victim would have been way too distraught to have done any of that.

In the docs, Rose says the woman only began to get upset with him a few weeks or months later because she felt she should have been reimbursed for one of the sex toys she bought and used during the night in question.

Rose says the woman got even angrier with him because he started ignoring her texts.

The woman is suing for unspecified damages. This week, Rose said he refuses to let the lawsuit change his lifestyle.