Soul Summon

Takes place before MAGE, all the way up to the beginning of The Man with the Mask Arc.

Heroes

 * Saganachi
 * Xeynar

Villains

 * Sontau
 * Soul Summon's First Villain
 * Soul Summon's Third Villain

Supporting Characters

 * Kiseni Saganachi

Mentioned Characters

 * Marlus Arsken Gerk Elus

Spin-offs
The spin-offs, in this particular situation, will be in its own world/universe. These are mostly intended for fun, and to reboot the series to be slightly closer to the series that was originally planned.

Soul Summon: Other
On Earth, there are a few people who have the ability to use 'Soul Summon', an ability in which takes on the form depending on the persons personality, likes, and natural fighting style.

It will follow the story of a shy boy who happens to stumble upon two Soul Summoners battling. Stopping, they feel the ability to use it, so one of them decides to teach him.

Sequel - Soul Summon: Universe
After Soul Summon: Other finishes, it's stated that it is only the end for the main character and his friends, suggesting that there are other Soul Summoners, either around the world... or even on different worlds.

Ultimately, Soul Summon: Universe is a planned sequel of Other in case it's popular enough. It may or may not have the main character(s) all be aliens; there might be some from Earth, but there will certainly be aliens in which participate (whether willingly or not) in Soul Battles.