The first film featured in Panik House's sensational Japanese 1970's exploitation film collection, Delinquent Girl Boss: Worthless to Confess, opens appropriately enough with a bunch of rough-looking delinquent girls watching a movie inside the less-than-cozy confines of their reformatory. Within minutes a requisite girl riot ensues after the principal has the screening stopped, and the aforementioned authoritarian soon finds himself the target of a roomful of unfocused adolescent anger, in addition to a well-aimed pair of pink panties. This type of unruly behavior requires a proper chastening of course, so before you can say Marco Polo, the giggling gals are sent off to avail themselves of all inhibitions and clothing, before frolicking in a hot, steamy bath.
The following day the film's heroine, Rika, encounters an old man wandering outside the reformatory's chain-linked perimeter. Rather than being a pervert on the prowl for some of that sweet delinquent girl loving, he turns out to be the worried father of a girl named Midori, who refuses to see him. The old man hands Rika a childhood keepsake to give to his daughter, but when Rika attempts to fulfill the old man's request, Midori angrily and mysteriously refuses to accept her father's gift.
Months later, after being released from the reformatory, Rika struts her stuff (like only a delinquent fresh from the stir can), and wards off a group of gangsters with her patented dose of tough talk and sass, before finally arriving at Midori's father's house to say hi and return the keepsake. The old man learns that Rika is without a place to stay, so he kindly offers her a vacant room in his humble home, as well as a job in his busy auto repair shop.
After this everything is all lug nuts and laughter until Rika learns Midori, who was also released from the reformatory some time ago, is continuing to run slipshod on her poor old father's lonesome heart. It turns out that his absentee daughter's boyfriend is accruing some pretty substantial gambling debts, and out of love for Midori, the old man is paying off the gangsters who are keen on collecting. Having become something of a surrogate daughter, Rika wants to help the old feller, but as she becomes more involved, danger steadily escalates until it's only a matter of time before Rika trades in her tire-iron for a samurai sword, and we find out why exactly it's worthless for a delinquent girl boss to confess.