Chapter 1 only:
I was super fond of the first one (I mean like, crying through the last chapter level of super fond), and this is shaping up to be even more fun. Even with just one chapter, so much potential drama has been set up, and the character has potential. Starting with a younger person (14) will making things interesting as well. It's not as unusual to emerge at that age than it is for the character in the first series (who changed at 17), but you've also got a character who doesn't have the stability of a best friend or a background of self-assurance (at a cost).
Sagara, MC, is an angry little boy who doesn't appreciate being mocked for his height (lack of) or his looks (too girly even pre-emergence), and he let out his anger through physical violence. Emergence weakens the body (and, in-world, so does simply being female...I'll have to mention this to all the guys I beat the crud out of in middle and high school...give them a real dose of ego, that), so that makes her usual fix-all of punching things, if not impossible, certainly more difficult.
Mamiya, the emerged character from the original, doesn't change so much in personality. He was a fighter, but in a competitive sense. She easily switched that spirit of fighting from more physical things into more mental things like school work and majong. With Sagara, it's not going to be quite as easy, I expect. Because he was mocked for his lack of masculinity, much of his character is built around shoving what he can of his masculinity (in this case, his strength) down the throat of the students who bullied him. Now, she is what she most feared, so she's going to have to seriously come to terms with that, and that story might very well be more interesting than the original.