The Unfairground dance tent gets really shadowy after the sun gets down, and Tokyo artist Sapphire Slows DJ set at 8 p.m. Friday matched the mood just right. Over the course of 90 minutes, she creeped between slightly unsettling house jams, acid-spiked rumblers and even some spoken word interludes. It was an absorbing set that worked best from front to back…stepping out for even five minutes felt like a mistake, as leaving the tense grips of Sapphire Slows mix resulted in some real sonic whiplash…and constantly found new ways to surprise listeners. Joining her on stage — Unfairground dancers and assorted performers, which helped take some tension off of the set. A fun little addition, though watching a dance routine while Slows played a speech about Marxism set over a beat felt a little too jarring.