Responses

well, more than being sarcastic the author is going according to the bible. lucifer (or satan, doesn't matter what you wanna call him) was thrown out of paradice for tempting eve to eat the forbidden fruit and because he was jealous of god's power.
so says the bible...
An angel ...who pissed off god
Sent to learn about humans and to redeem himself
Sent to do penance on earth as a undertaker of all things
This mangaka understand irony ,and sarcasm .
Problem...it's too short ... would be wonderful If it continued until he finally regains heaven
And with the understanding that humans are worth the effort
But my advice would be to maintan the sarcasm ...it makes the story worth reading