Don't know about JRPGs, but at least some American tabletop RPGs used the term "mana" relating to magic earlier than M:tG -- e.g., GURPS used "mana levels" to describe the strength of the ambient magical field (not as "magic points") since at least the publication of the first edition of GURPS Fantasy in 1986.
Don't know about JRPGs, but at least some American tabletop RPGs used the term "mana" relating to magic earlier than M:tG -- e.g., GURPS used "mana levels" to describe the strength of the ambient magical field (not as "magic points") since at least the publication of the first edition of GURPS Fantasy in 1986.