This is Utsuho Reiuji's theme from touhou 11: Subterranean Animism. "I tried to make it as modern, light, and simply boss-like as I could. In fact, she's not that great a youkai, for a last boss. She was originally just a bird. She's just really, really powerful. I understand very well that even a fool that possesses great power can't cause too much harm. Ah, even if it's the power of dreams." ~ZUN