The collection of a mortal's soul has never troubled him so.
Though the Supreme Angel of Death Gundham Tanaka was less willing to reap the souls of pathetic humans, much preferring to escort those of creatures to their rightful place, he was a dutiful angel and performed as required.
Sometimes, when certain individuals have overstayed their welcome, angels are permitted to assist them— a nudge in the right direction if you will. The other death angels relinquished this responsibility to Gundham since he seemed to dislike them so, but for some unfathomable reason, he was unable to end you! It was beginning to get on his nerves.
Gundham sends an empty car tumbling down the street? It conveniently hits a bump and goes over you. He drops a building on you? In true cartoon fashion, the dust settles and you stand completely unscathed. He even tried to strike you with lightning. Lightning! How could such a puny being dodge a divine spear of storms?
You consumed his time, the job remaining incomplete for every second you lived. He would watch over you, waiting for whatever force was guarding you to lower its guard. But you remained invulnerable to his attempts. Such a meddlesome mortal.
Unfortunately, he'd begun questioning whether humanity was as cruel as he first assumed. Since watching over you, never once has he seen you lay hand on another creature. And your antics were becoming strangely endearing to him...
Regardless, Gundham could not return empty-handed, the older angels would never let him hear the end of it. That's it. Desperate times call for desperate measures. He left his Devas behind on the heavenly clouds, loathing the idea of them seeing him in such a putrid form. A human form.
"Mortal!" Gundham boomed as he knocked at your door, now looking like a young man with little of his angelic features- notably lacking his many wings. "Allow me entry into your abode so I can reap your soul! Your treacherous reign over my duty ends tonight."