Am I the only one who's confused? Who's the oniichan and oneechan here? They're supposed to remember the angels because why? It was sweet though but the context!!!
@artdeer Nah, the TL is just very awkward.
The angels come down to watch over certain people. They present themselves as a someone close to the person, and that person isn't supposed to be able to tell that the angel is actually an angel.
In this case the angel pretended to be the guy's sister, but he realized she's an angel, which is why he's an exception.
The girl's disguise was blown anyway, so she decided not to keep up the act, and was just lazily spending time at the guy's house instead. He was nice to her nonetheless, and she fell in love.
@iltrof Ohhh that now makes so much sense. Thanks! "Humans should recognize angels as an existence that has always been there" is vague and confusing as opposed to "Angels present themselves as someone close (this right here, as opposed to just 'an existence') and the humans duly recognize that person."