Reddit wasn't much help to me, so hopefully someone here has an answer.

Either a japanese or korean horror film. Set in a high school. I think the girls are posessed or something. All the males seem to die in the movie. 

What i remember is the ending shot,  the girls kill who i think is the male janitor. All the girls look happy, in blood, they start dancing around the class room to the song end credits " sisters ,are doing it forthemselves".  

Its been prob 15 years since i saw this at late night tv.

Google AI comes up with this

I really wanna know what situation you are in that you want to find out what this film is. Must be crazy.

Lol, not everything in life is as crazy as it seems.  But to answer why, i hear that song everyday at work and i get flashbacks to  that movie, and got me curious.

Unfortunately ai got it wrong this time..

This song?



This is probably not it either

"The Eurythmics' song "Sisters Are Doin' It for Themselves," featuring Aretha Franklin, is used in the end credits of the movie "The First Wives Club" (1996). It plays during the construction montage where the female characters are transforming their revenge warehouse into a support center for women"

The Eurythmics' song "Sisters Are Doin' It for Themselves" was used in the end credits of the movie The Girl with the Dragon Tattoo (2011)

https://www.what-song.com/song/258552/sisters-are-doin-it-for-themselves

Yes, this is the song that was used at the end credits , while the girls were dancing in class with blood and gore, having the time of their lives.  Girl power indeed, the song choice kinda makes sense lol. But i need to find the damm movie title

You mean "Tag"?

Nostalgia is a bastard of an emotion. 

Only two films come to my mind, but I don’t know if they quite match:
Suicide Club and Battle Royale.