I recommend the Water Hair Treatment. Since it is a liquid type, it is easy to use, and it doesn't take long to rinse out after application. It is nicknamed the "Water Seaweed Treatment," and it definitely improves hair texture. Also, there are two types, Miracle x10 and x100; after trying both, I found that the Miracle x100 is definitely better, perhaps because it is a more highly concentrated ampoule.
Anyway, I recommend a water treatment that is great for simple use in the summer.