as for secret i believe it is enough to read the translation to grasp its meaning
http://ayumi.primenova.com/lyrics/secret.htm
she isn't free and her days feel like they are empty even though she is seen as having everything. she does not have the courage to change things even when she is sick of the situation.("even when i am tired of flying with my only wing left i dont have the courage to rest"). she wonders how she is looked in the eyes of others (surely as if she had everything and is happy and strong) while saying that the truth is that "even now i am looking for a place to fit in". same lyrics as a song for xx. it is heartbreaking if you ask me