Tezuka Purodakushon.

Set in futuristic Metro City. When a brilliant scientist's young son dies, he secretly creates a powerful robot boy he names Astro Boy. Unable to fulfill the grieving man's expectations, Astro Boy embarks on a journey in search of acceptance. Along his way he experiences betrayal and a netherworld of robot gladiators, before he returns to save Metro City and reconcile with the father who had rejected him.