I recommend the Donggubat shampoo bar.

I tried a shampoo bar by chance, and it had far more advantages than I expected.

It lathers well, and my hair doesn't get as stiff as I expected! Being an eco-friendly product is a bonus, too!

As for the downsides... honestly, I'm not really sure.

They even had a separate treatment bar!

It's not a bad idea to try it at least once.