There is a place far away, and there is an orphanage that adopts "angels".
The children there have wings as white as angels, except for the cattails and crows named "fallen angels".
Daily "physical examination", "minor surgery" to become an "angel", overheard "Seraph Plan"...
The ominous black wings and their similar appearance are leading them to the final outcome.
Spoilers(?):
——I will make up for your imperfections, so do you want to come?
——What a sin, the eldest lady is actually mute.
--Aphasia? Ah, whatever. With the same virtue as her sister, give up.
——It's better to send him away quickly, so as not to leave a laughing stock to the family.
——Isn't the young master here? Just have him.
Notes: 1. It has nothing to do with "Seraph of the End"
2. Imagination triggered by my two pen names