Gothique Resonance

I find this chart insanely difficult for a D13. The half is confusing and it even has some level of leg split. There are quite a few D15s easier than this one. Still, it’s well-made and good for practising.

Purely between 13 and 14 in terms of difficulty, and since it's a concept chart, it's very helpful.

One of the charts considered a "fundamental" chart; it's on the harder side, but it helps improve your skill.