I guess you have a point but... [in fact being embarrassed would not stop Yoosung from absolutely loving it if someone called him pet names, but that is clearly neither here or there!]

Well, it was already kind of a thing when we started calling each other our first names! Korean and Japanese normally only do that with the people we're comfortable with. I think that's significant enough for how we relate.

[Yoosung is confident this will be a satisfactory answer. He's a little flustered still, but he didn't think anyone else would have thought he was something different to him from the sunbae role he was thinking about. After all, that explained perfectly when it came to his manic fixation on both being acknowledged by him and keeping him happy and safe.

...But if he thinks about it that way, it isn't unlike the girl in the apartment...]