Lee, Youngran

Joonha confesses her darkest secret to Heewon, who makes her promise that it will be their secret forever. Later, Joonha ends up in the hospital and is given one last chance to decide her romantic fate.

As Jinhoo develops even stronger feelings for his friend, Joonha, he decides to see a psychiatrist to sort things out. Meanwhile, Taehyun confesses his feelings to Joonha, and Joonha becomes jealous of Jihan for hooking up with his old girlfriend.

When Jinhoo discovers that Joonha is actually a girl, he wonders how this will impact their close relationship. Meanwhile, Heewon attempts to discover the truth behind Joonha's gender identity.

Taehyun knows that he feels something for Joonha, despite Joonha's gender confusion, but is thrown for a loop when Joonha's childhood friend, Jinhoo, arrives back in Seoul. Joonha seems prepared to continue their relationship, even though one of the boys is now a girl. Jinhoo appears carefree enough, until trash-talking Heewon confronts him with a startling revelation.

Shortly after Joonha and Taehyun team up to take down a vicious card shark, several figures from Joonha's past emerge and begin to cause trouble.

Transsexual Joonha moves to a new city and lives as a girl in her new school. Taehyun coerces her into a friendship and frustrates Taehyun's ex, and Heewon reappears after following Joonha all the way from her old school.

As Jinhoo and Taehyun battle it out for Joonha's affections, Joonha receives startling news from his father that allows him to face his future with new hope.

When Joohna turns sixteen he discovers that his family has a strange chromosome mutation that causes them to change sexes. So as he becomes a high school student, he changes into a she and leaves his old world behind to do it.