Complex sentence: Most full-fledged mangaka started out as assistants, such as Miwa Ueda to Naoko Takeuchi, Leiji Matsumoto to Osamu Tezuka, and many others.
Split into simpler sentences: Most full-fledged mangaka started out as assistants. There are many mangaka that started out as assistants, such as Miwa Ueda to Naoko Takeuchi, Leiji Matsumoto to Osamu Tezuka, and many others.