"To Choi Seung Hyo in 10 years, having to write a letter like this is really childish. Bae Seok Ryu keeps asking me to do it, that is why I did it, well whatever, i'll just write it down for now. Probably by that time you have already participated 3 times at the olympics right? You must have participated in many world championships, and became a complete veteran player (swimmer). Olympic medals descends from the sky so, I don't know if you won a medal or not, but I hope you will not regret the outcome. As long as you have enjoyed the process, that is enough. But still, I couldn't imagine it yet. 10 years from now seems so far. By then, you must have already confessed to Bae Seok Ryu right? To be honest, I don't know when I have started to like her. We have been together since we were very young. I started swimming because of my asthma however, I think it was because of Bae Seok Ryu that I wanted to swim well. Just in case when Bae Seok Ryu who is afraid of water falls into it, I will be able to save her at anytime. And I realized as I looked at the girl who skipped her exam to cheer for me at the time when my mom and dad didn't come at my game (swim tournament). After meeting Bae Seok Ryu, there was never a moment when I didn't like her. But I don't have the courage to let my feelings be discovered/caught because i'm afraid that our friendship would be ruined. So, instead of now, I hope that after we become an adult over the age of 20, I will be able to convey my feelings for Bae Seok Ryu well at that time."
p.s I tried my best to translate this as accurately as I can, if there will be mistakes, I apologize in advance hehe