Complex sentence: In the early Matsushita-centered stories Takagi was more of a supporting character, but quickly grew to become such a fan favorite that he soon wound up as the main character for the rest of the series.
Split into simpler sentences: In the early Matsushita centered stories, Takagi was more of a supporting character. But he quickly grew to become such a popular fan favorite that he soon wound up as the main character for the rest of the series.