Hong Kong —  The buzzing of needles and gasps of pain fall silent, replaced by the clacking and rattling of steel and plastic colliding. Normally, visitors to this small tattoo parlor tucked away in the backstreets of Hong Kong’s bustling nightlife district, are looking to be inked with tigers and dragons, representing the halcyon days of the neon-lit metropolis. But it has drawn a vastly different crowd. With the tattoo tables pushed to the side, the room becomes a coliseum for adults going to war with Beyblades, a children’s toy made popular a quarter of a century ago. The customizable spinning...