Biscuit Krueger first comes into the story in Greed Island. Although she appears to be a little girl, in her true form she is actually a massive and extremely muscular woman several times the size of her preferred form. The only reason she stays in her girl form is because she claims she hates her original form's appearance. Regardless of which form she is in, Biscuit is very powerful. However, she does receive a tremendous power boost when she transforms to her real appearance. She helps Gon and Killua train while they are at Greed Island, leading them closer to the end of the game. Her goal in the game was to get the gem found only in that game, Blue Planet. She prefers to be called "Bisky."
Source from Wikipeida