Summoned as a Demon Lord. Reincarnated as an A.I.. Transmigrated as an Assassin. What's going on?!

Brief summary of the plot: Guy breaks up with cheating girlfriend ends up getting summoned as a Demon Lord tasked with world domination, Reincarnated as an Artificial Intelligence to save humanity from an extinction level extraterrestrial threat, and transmigrated in the body of a crippled assassin left for dead who eventually gets summoned as a hero to defeat the Demon Lord. All at the same time...