Leo: I've heard of you, Thanos! You're a demon!
Seven: A demon, Thanos! You tried to indiscriminately wipe out half of all life in the universe, including humans! We'll stop you, no matter what!
Thanos: ??? I'm just a passing purple potato spirit. Why would I do that? I don't want to get involved in some population-control office nonsense here! I just want to fix my Infinity Stones!
Zero: Let him see the power of the Ultra Warriors!
Thanos: Ganging up on me? Cosmos and Orb are both on my side! Let's see how you manage to combine Saga and Reiga! If I find out who spread this rumor...
Tartarus: Yeah, whoever spread that rumor really deserves to die. (deadpan)
Thanos: ...
The protagonist is Thanos, but he's a transmigrator, essentially possessing another body. This is the story of a former office drone, former Dark Lord, and current passing purple potato spirit, frantically grinding away in the Ultra universe so he can live a lazy life until he dies.
Progress: Orb: Origin Saga (The Ganon Arc to the Earth Arc) - Ultra 10 Warriors - Gaia (abridged) - Tiga
The story is divided into volumes.