Raws for chapt. 16.1 are out and... sorry not sorry for Uzume, but your actions were what pushed Shinba away from you
Now with the raw:
sadly, Uzu... Miyabi Amano, during her childhood, was the popular type for being a child actress, but kids only talked to her because of that and asked her for connections to meet other popular actors or idol songers, making her pent up some anger. Shinba (deemed as the class otaku) was the 1st who talked to her as her real self (Miyabi). A montage of her life outside school (classmates asking her for connections to meet idols, producers demanding her more effort bc she wasn't gonna be a child actress anymore and mom telling her to get used to live on her own) and how Shinba was her only outlet to a normal life (he also gave her an Umbrellaman figure) and how the reason for her to reject and leave him was because her mom told her to go to the United states. There, she swore herself to rise as a star, become the couple of a celebrity and not letting herself be dragged down by a loser like Shinba, deeming said crush as an adolescence fling, but one night in her solitude, she saw the photo she took with him and the Umbrellaman he gave to her and began to cry a river.
Back to the present day, Shinba overhears, Miyabi once again tells him her feelings, but also that she couldn't reciprocate back then because she didn't know when she was gonna return, so she could neither ask him to wait for her, and she had the plan to confess to him once she returned because she thought he was gonna keep being the same unattractive loser he always was (is) and by rejecting him, she was gonna also stop being childhood friends with him, but it happened she saw how he found another person, and there was no reason for her to be next to him if she enacted her plan to confess to him, only to be rejected. So she made all that plan (as seen in chapters 12 to 14) of making him remember his memories of his first love and then let him confess again. Shinba tries to counter, but Uzu... Miyabi tackles him to the ground and angrily demands him an answer on which kiss felt better to him, hers or Hizumi's. And that's how the 1st half of ch. 16 ends.
Imo, Pretty sure Shinba is gonna reject her back the next chapter, and Namikoi is gonna be one of the reasons, the other, obviously Hizumi and how she stood by his side despite of his own patheticness