Red

 The 'red'. To give hint for this, think about national flags. What is the flag with red cover? It's China. China is the place where I spent my time of youth. I went there at 6 years old and came back to Korea at 11 years old because of my father's business. At there I attended the national school and had a delightful time. Even though it had passed long time after I came back to Korea, I still dream me playing in China with my friends. The time I spent there is so memorable to me.