I messed up, he holds his breath, the ribbon in his hair slipping off. In the seconds that it takes him to reach, all the memories that led up to this point—pieces from this morning mushed with fragments of recollections from months before—begin to flood his mind endlessly.
By this point, tears fall uncontrollably and his lips have gotten bruised from biting down on them so hard, as if it's a punishment worthy enough for what he's done.
I messed up, are Mizuki's final thoughts as her lungs are filled with water, leaving no room in her chest to breathe. As she sinks lower and farther, she thinks about Hinata and no one else—not even the fact that she's not going to make it home, or if she's going to ever exist again if she dies here.