It's pretty funny how quickly "this world has gunpowder now" is swept under the rug so we can move on to cute girls school schenanigans. To be fair though, they are extremely cute
To be honest Gunpowder weaponry development speed was slow enough IRL that it makes sense that it's not a ridiculously big deal in the story even without taking the Slice of Life angle into account.
The weapons were frequently outdone by older/more traditional methods for quite a while.