From Wataame Shoujo:
Yoo-i is a very special girl -- she's like refreshing and fragrant orange bubble gum... A boy appears all of a sudden and becomes a natural part of her life, as natural as breathing air... His name is Joo-in. He says, "Do you know nuna? Nuna is.. my past, my present, and my future... You are like this ladder connecting me to this world..."