Tatsu no Ko Tarou

Both made in the 60s/70s and center around a mythological young hero boy. Isao Takahata worked on both films. 

Both "Taro the Dragon Boy" and "A Deer of Nine Colors": - are fine examples of folklore-based animation; - contain a teaching moment; - have nice artstyle and colors; - are quite old yet extremely enjoyable. 

Both are fairy-tales based on mythology and both have old-style animation. 

Both involve magical spirits and creatures natives from japanese culture and a child who needs to understand and learn the importance of their people and lands, which they need to save from the threats of malicious humans and selfish creatures.