@The Riot lore Team; Lee Sin's Lore

Since Lee Sin will eventually be getting a lore update I thought that I should ask this question now. I have always wondered why Lee Sin uses energy? The only other champions that use energy are the four ninja champions. I have always speculated that this was because Shen's father trained Lee Sin. However this conflicts with a few other facts. I don't think Kennen or Alkali were trained by Shen Father. If I remember correctly Alkali was trained by her mother. Also I know Lee Sin was trained by the monks, but I always wondered if thats the only place he trained. I figured that they also didn't want Lee Sin using mana because he swore never to use magic. However I don't consider a lot of other champions that use mana to be using magic on there abilities.

TLDR

Why from a lore stand point does Lee Sin use energy?