I thought, Nasa-kun was a reincarnation of a accent someone who had met tsukasa and had a crush on her or something, and the person pushed nasa to wake up and chase tsukasa, (happen in chapter 2 and ch. 144, said "miracles never happen twice" when he passed out), and through the fragment we can...
@feha @Oldgalaxy Rereading the chapter, I suddenly realized that kouhai was a wingwoman(to push her friend to confess) and the dog collar might be a funny excuse that makes no sense. Since the kouhai said "that's not important." to change the subject. lol