It gives me a refreshing feeling right from the intro. I feel like I'm the main character in a youth movie. The melody is bright and the lyrics are hopeful and give me strength. The members' voices are so clear and harmonious. It's really thrilling when the rhythm explodes in the chorus. It's a refreshing song that's perfect for summer. My mood clears up the moment I listen to it. It's full of fresh excitement and a feeling of freedom. The repeated "Knock Knock" part stays in my ears. When I listen to it, I naturally find myself singing along. It's a song that resembles the moments of youth. When I listen to it when I have a lot of worries, my heart feels lighter. I like it because I can feel ASTRO's unique bright energy. It's a song that goes well with the clear sky and the wind.