Whenever Nitori makes a move (note that she stays still and moves at set intervals of time), her horizontal movement will be toward you. The exception to this is if she's too close to either the left or right edge (maybe within 1/6 of the screen's length), her next move will be toward the center, regardless of your location. In my example, I hover above the "m" in "enemy" as the card starts, which lures her to the right for her first move. I then wait in the lower right corner to once again lure her right, and to mislead the incoming aimed pellets. (You could just wait in the lower corner from the start to simplify the luring process, but staying near her at the beginning adds on a bit of damage, which is always nice since Touhou is a game of pixels and milliseconds.) After she's made two moves, she'll be too close to the side and make a move toward the center, so for the rest of the card, I'll stay to the left of the second "e" in "enemy" as much as possible to continue luring her left until I've drained her health bar.
I apologize if this doesn't help, since I didn't actually say anything new and only restated part of my previous post in extreme detail.
Also consider that this is only my method of doing things. There may be another method that will work better for you, so if this doesn't work, try experimenting with Baity's method or experiment with your own.