Is This Still Bandori? Where the Hell Have You Taken Me?!

Just as Arai Yu, fed up with all the red tape, was about to have a heart-to-heart with Radahn, everything went black, and he found himself in a completely unfamiliar otherworld. After living a peaceful life for eighteen years, Arai Yu graduates from his teacher's tutelage and is finally ready to begin his own otherworldly adventure. But when he sees those familiar yet unfamiliar faces, Arai Yu can only sigh. Will someone explain why there are band girls in this medieval fantasy world? And without instruments, can they even be called a band? No, no, that's not the issue! Is this even BanG Dream!? Where the heck have I ended up?!