Complex sentence: Rumors concerning Kitagawa and possible sexual harassment of the youth in his employ had surrounded the agency since 1988, when, a former member of Four Leaves, published a series of diaries under the title.
Split into simpler sentences: Rumors concerning Kitagawa and possible sexual harassment of the youth in his employ had surrounded the agency for several years. In 1988,, a former member of Four Leaves, published a series of diaries under the title.