Black Shlack is a character in Panty & Stocking with Garterbelt. It has the shape of a blue snake, and was one of the main antagonists in "King Molomon's Treasure: A Romancing Adventure", the second strip of the In Manga special.
This ghost appears to have katanas tied around him, along with one katana in it's mouth. It was summoned by the demon sisters to kill the angels at the summer festival. It is a ghost that was believed to have been caused by generations of hate. It was eventually killed by the Anarchy sisters, aftet they threw their demon-made weapons at it.