I've played volleyball since I was 8 years old, so it's no surprise that a volleyball anime is in my Top 3 favourites. Here's how I tackled styling their uniform and the dreaded colour orange...

"Today you are defeated, but what will you become tomorrow?"
- Haikyuu, 2019

Pick out your highlight colour and work with it! The white details and jacket make the look cohesive.

Easiest way - oversized pants! The little shirt/big pants combo never fails.

Don't forget your bag! While it may be functional, it's still part of your look.

The base garment can be totally unexpected. This is a thrifted sundress. Tie it up higher to transform it!

Don't be scared of orange - lean into it.

Mini skirt and boots make it less 'athleisure' and more 'punk'.
Now, these are all very basic tips for styling but when wearing merch you want it to be the focus even if it's subtle! I always say the best way to elevate an outfit is through accessories - this makes the look very intentional rather than "something you just threw on". The Karasuno uniform from Haikyuu! is one of the most iconic sport uniforms in the anime world and I think this is a very cute and creative way to grab the attention of other fans in the wild.
Unfortunately, the shirt was a gift so I have no sources where to buy. But there's many similar options on amazon! The hoodie is from Fandomaniax.
Links below!