User blog comment:Imouto-tan/Magical Energy/@comment-4867780-20170113115308/@comment-26362471-20170114013612

Yes, Ki comes from the environment and Mana from within. (just correcting the first sentence ^ ^;)

Not quite as Mana Crystals are solidified mana that can be created from either two Jewels collide their spells together or from the Earth itself via Magic Clime caves. Magical energy fuels every type of magic and nearly every magical artifact; mana fuels the person and spells that originate from their Jewel powers, whilst, Ki fuels non-Jewel ability spells and is more associated with hand-to-hand combatants and nature spirits.

It depends on the spell being used, as some spells need certain atmospheric conditions to be met before they can be used. I.e a powerful lightning storm spell or a blinding smog spell. Rain, however, does affect Ki a little bit as it disrupts Ki related teleportation and tracking.

Espers don't use mana or ki and the type of magic that the person uses isn't affected in anyway by the amount of Ki in the surrounding area as everyone has a certain amount of mana and ki they can use at a given time.

Ki may restore slowly, but that's why there are alternate ways to cast spells and use magic. I.e. Magic Apps

More Jewels and magic users use their own mana to cast spells while humans use more Ki and rarely over uses it as they use it to boost physical attributes for combat.