Not only that but doesn't it directly contradict the established lore that Takumi has been in love with Ayako since he was a child? Also as far as I'm aware he didn't move away or anything so how did he have a middle school/high school romance with another girl while within close proximity to Ayako and nobody knew about it? Takumi and Miu have been childhood friends since they were both kids (Takumi was even at Miu's parent's funeral, in fact it's where he fell in love with Ayako) and Miu never mentioned it either.
Actually looking back in the early chapters, Chapter 1.4 literally page 1 Takumi says he hasn't had a single girlfriend yet when Ayako asks him about it. Either this is a retcon or something else is going on like he had to pretend to be her boyfriend for some stupid reason. They've already made significant progress for the Ayako x Takumi route so adding pointless drama that the audience knows isn't going to go anywhere (because Takumi himself has repeatedly mentioned he hasn't ever had eyes for anyone else) is just filler and a waste of time.
The only future for this new character is to show up, cause trouble by making Ayako second guess their relationship (again), then disappear like a fart in the wind. Why do authors do this shit?