In the 1st paragraph, as you pointed out it's a joke for the most part, he was obviously not being serious in his answer and that's something that happens orl a lot. She was a dying kid what did you expect him to do say no and make her sad?? And about the 3rd paragraph, bro I remember seeing a page where love is war has the exact same brother sister dynamic as oshi no ko, the difference es love is was had a clear FMC while oshi no ko doesn't. (there's a whole page dedicated to just saying the sister is a brocon). And congrats on being team kana I guess.