Complex sentence: Ten years prior to the start of the series, she and Kodaka ("Taka ") are childhood friends, but because she has short hair and wears a cap, Taka mistakes her for a boy and calls her"Sora".
Split into simpler sentences: Ten years prior to the start of the series, she and Kodaka ("Taka ") are childhood friends. Because she had short hair and wears a cap, Taka mistakes her for a boy and calls her"Sora".