I've had some ideas for a RanmaXShamanKing crossover rattling around my head for sometime, and I'm finally getting around to working on it, but one thing that continues to bug me is that I can't figure out how KI would interact with Mana (I.E. Furyoku).
As far as I know Ki was only mentioned once in the manga(I'm not sure if it was mentioned in the anime). Lyserg mentioned it in volume 11 as a person's spiritual energy (somehow different from Mana), and that he could use his divination oversoul to track it. Though the Patch could hide theirs to prevent detection.