I played that game so long ago and by the time you got to that boss you were already accustomed to bullet hell, so this boss was still hard as **** but I still did beat it. Japanese people really know how to make good and hard games
It seems like the final boss is basically about knowing where to put your airplane and then move it centimeters to either side.
I dont know if thats skill or just pure trial and error.
Still completely overwhelming for someone who has never played that game.