Nightbringer yasuo not in store but in champ select

it will be out next week just like every single fucking skin before it.

Going into champ select on my main and seeing a skin that I can't buy is gaaaaay

This happens with almost every skin now. It's added to the game in the patch that it's going to be released in, and you can see it from the Collections page or champion select, but you can't buy it until it's actually released.

And Riot was vague with the announcement on the whole VS. event thing. It may even be that this is a skin you don't buy.