As big as this chapter was for these two people, Ueno has a much bigger challenge in front of him, at least I think so.
He hasn’t yet talked to Manaka about his past and the circumstances that he’s still mired in. He knows a fair bit about Manaka’s situation, not everything, but enough. On the other hand she’s completely in the dark and that imbalance isn’t okay.
Ueno isn’t being honest about who he is or who the three women who bully him are. These are also people that Manaka thinks are her friends, remember? Except that they initially approached her to mess around with Ueno.
Protecting Manaka from uncomfortable truths is disrespectful and takes away her agency to make informed decisions. She is in danger and doesn’t realize it because she’s trusting people who don’t deserve it.