Around 5 pm Sunday, Ms Das was heading home from karate classes at Barasat when two bicycle-borne men accosted her. One grabbed her hand. She pushed, fell, got back up on her feet and hit back.
Earlier this year, Ms Das won two gold medals at state championships for karate. But the men didn't know that, nor what hit them.
"I grabbed the throat of one of the men. As he started choking, I punched him in the face. A few snap kicks to his neck, some groin kicks - and he fell down groaning. When they started fleeing, more kicks on the back. They went sprawling," Ms Das recalls.
Tough words and actions from a five-foot-nothing girl who left school after class 8 when her electrician father could not make ends meet. She was upset that bystanders did not help when she was attacked and hopes the molesters are caught soon.
Her karate master Bholanath Shaw, a national gold medalist of 1996, is very supportive.
"I am very proud of Munna. She will inspire thousands of girls to fight back if attacked. All women must learn self-defense these days when molestation and rape have become so common," Mr Shaw said.
With her free time, Ms Das teaches karate at some girls' schools for a living. She wants to open a karate school of her own especially for girls.
"I am a great fan of Bruce Lee. So I took up karate as a sport. But after Sunday's incident, I think self-defense is a must for women. I know what I want to do. Teach girls self-defense," she said.
Training for a year and a half now, Ms Das will take the test for a black belt next month. On paper, Munna's name is Munmun. She prefers the short form.
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