Yeah, the early games are rather strange and only somewhat canon, though still worth playing if you're into them. Embodiment of the Scarlet Devil, the first Windows game, is the go-to starting point, though some of the other entries might be more forgiving if you're bad at SHMUPs.
btw, aside from kaoru's cute annoyingnesss why does chisato snob our poor lady killer anyway
i never understood why is it explained in the game stories?