These are the official Kill la Kill glitter pants, or leggings/tights as they seem to be in the modeling video, as released by Felissimo alongside their host of other KlK products like the false nails and scissor sword pendant.
They are intended to be worn with a skirt being labeled as tights, but there’s a reason you may wear them alone.
Yes, it would a be shame to show off your fandom of choice without getting into the spirit of having a big glowing, pink groin. There’s a closeup of the material, and it is thick enough for these to be really tight pants. So if you’ve ever wanted to spice up your yoga routine or just be the best host ever to people coming to your home, you have the ability.
You can order the pants for ~¥3,000 here.