Into a different world (HXH and MHA crossover)

It was a normal day for Gon and Killua who had just reunited a year after being separated. They were both 15 and living in an apartment in York New. Alluka had insisted on staying at Whale Island with aunt Mito.
"Killua let's get that cat!" Gon had said, on their way to a café, running into an ally following a strange cat.
"Don't just run off BAKA!" Killua yelled but nevertheless followed his idiotic friend.
Little did they know that this was no ordinary cat, but a cat that would turn their whole world upside down; rather take them into another world.
How will Killua and Gon cope in a world where killing isn't the norm and where being a 'hunter' meant nothing, but instead 'Pro heroes' are at the top of the food chain.
And are Killua and Gon the only victims of this mysterious cat?