K18 is still fairly new, but it’s already an if-you-know-you-know brand name among hairstylists, colorists, and celebrities, like Hailey Bieber. The leave-in treatment even won an Allure Best of Beauty Award in 2022. Refinery29’s Beauty Director Sara Tan is a big fan, and I’ve heard it compared to Olaplex (one beauty editor even said it’s better). TikTokers are sold, too, with the hashtag #K18 gaining an impressive 415.6 million views. So what’s in this seemingly magic hair potion? And is it really that special?