Anju is Yuu's old childhood friend and first love. He calls her "Anne" because of her favorite book, "Anne of Green Gables". She is a very soft spoken person and has been in love with Yuu since 6th grade. The run into each other in episode 36 and she meets Miki. She respects Yuu and Miki's relationship and does not want to come between them. She really only wants to see Yuu when Miki is not busy with him. In fact, she tells Miki that she is in love with Yuu and wants to be second to Miki. Miki is confused by all this but she really likes Anju so she gives in to her.
Anju has a very serious heart condition. She had been in the hospital when she first met Yuu and was in the country recovering. She noticed a young Yuu was looking sad wanted to cheer him up. She hits him over the head and he chases her and they quickly develop a friendship. Anju's heart condition is very severe now and only a life threatening surgery can save her. She collapses in the Christmas episode and wakes up to see Yuu by her side. She tells him to go home to Miki and that she has gotten over him. Anju leaves for America in episode 42 to have the surgery.
Anju comes back to the show in episode 59 when Yuu and Bill run into her in New York. It is noticed right away that An and Bill just might make a good couple.