Young Juvenile Youth have had a series of starts and stops to their career thus far. They gained momentum…and then kind of dropped off the grid for a second. They play a Hello-Kitty-themed park in Tokyo at a big Halloween show…and then are quiet. Well now the duo’s debut album, Mirror, arrives next month, and “Slapback” offers a first glance at what they are up to. In many ways, Young Juvenile Youth’s visuals have always gotten more priority than their music — they got robust coverage and fan attention for a video, not a song — and this one features a pretty flashy (and disorienting) clip to go with it. But there music often does warrant just as much attention, and “Slapback’s” vocal-sample raindrops and off-kilter electronics lend the song a wonderfully unsteady feeling, giving it the feeling of always being unpredictable. Yet grounding it, as has always been the case, are the vocals, which give it a human feel thanks to the dilemma at their center. Watch above.