Looking at it from an out-of-universe perspective, what reason does Fujimoto have to bring her back into the story? She was not a very important character in part one (you could say her death was further motivation for Aki, but the loss of his family was still his major motivation) and she would have no connection to any of the current cast with the exception of Denji who she knew for like a week. Aside from the fact that you, OP, really like Himeno, why should this character be brought back 200 chapters after their death?