User blog comment:Imouto-tan/Magical Energy/@comment-4867780-20170113115308/@comment-26362471-20170116050459

You are very welcome. ;)

Indeed, magical energy is what used Ki and Mana are called, Magic Clime caves are caves made from the remains of Celestial Beasts, ergo, the caves have mana inside of them. Most mana clime caves aren't naturally occurring and were made by powerful mages with their mana.

Not exactly no, while some powerful spells do use Ki to sustain themselves not all of them do and the only time that using Ki becomes a problem is during war. Despite how it sounds a C-Rank mage can still do battle even in Ki deprived areas, I would love to explain how Jewels work, but it seems that you didn't read the Jewel sheet well enough. Jewels can function fine without mana and even normal humans have other means to do battle without Ki.

Magic Com-Devices (which Magic Apps are on) use mana to operate and some even use electricity as a fuel source.

Use of magic outside of tests and exams is illegal and violaters will be punished, however, Destiny City uses only green energy and rarely uses Ki for their daily lives.