Most manga serials didn't delve into any crossovers, but GHOST SWEEPER MIKAMI (1991) crossed over the main character, Japanese exorcist Reiko Mikami, with the folkloric character of THE PIED PIPER OF HAMELIN.
To be sure, it's really just a minor demon that tosses together a lot of tropes from the Pied Piper story and reworks them for its own convenience (much like the manga author), such as changing adult humans into children or controlling rat demons. But one could argue that it's still a loose adaptation of the original, though it counts only as a "high-charisma" crossover.
