The style of weapon and the girl's more modern hairstyle and uniform are visual cues that this is not from the Imperial Japan period. It looks like a still from a "sukeban" ("girl boss") or similar film, possibly from the late 70s or early 80s.

"Sukeban" films were a briefly popular genre in the early 70s featuring delinquent high school girls, mirroring a concurrent social trend in uniformed high school girls hanging out with their gang-member boyfriends. Sukeban wore long skirts and frequently toted about their kendo practice swords and engaged in anti-social behavior such as glue-sniffing and shoplifting. The real life sukeban grew out of this phase and are now all middle-aged, but the idea continues to crop up in movies even today.

Generally speaking, whenever you see a still of a Japanese high school girl in a long skirt wielding a weapon- even one as over the top as this- it's more than likely sukeban or inspired by it.

And now you a little bit more about Japan.