Though not specified, Echo may be based off of Yamabiko or Yobuko.
The yamabiko (山彦) is a mountain god, spirit, and yōkai in Japanese folklore. The term "yamabiko" is also used to describe the phenomenon of a delayed echo in mountains and valleys, and is thought to be the spirit answering. In this case, it is written as 幽谷響. This anomaly is also sometimes called "kodama", when it is thought to be the answering voice of a tree spirit (木霊 or 木魂).
In Japanese folklore the Yobuko (呼子 Calling child?) is a yōkai (a supernatural monster) thought to reside in the San'in region and the city of Tottori. It was believed to be the cause of echoing. The Yobuko was thought to live in the mountains, and whenever a traveler entered the mountains and raised their voice, it would mimic them and call back.