I don't know if I only noticed it these last couple episodes, but the slight echo that makes it sound like voices are travelling further underwater helps a bit to make up for the buoyancy problem I had.
With this series now being 26 episodes, they've started to expand on his character. The extremely uncomfortable scene with his mother was quite telling that beneath that calm, knowing, aura, some things are not at all well.
For a while, I was hoping that the hibernation wouldn't occur, but now I'm really looking forward to it and desperately hoping that it is both short, and extremely asymmetric. They've been foreshadowing that possibility heavily, restating every episode that people won't wake up at the same time necessarily.
I'd love to see all of them fall asleep, but because Hikari has been eating (as have the others to a lesser degree) wake up at mostly different times, with the rest of the Shishishioshishishi residents remaining in hibernation. Perhaps something with the town now regularly performing the ceremony, and thus messing with the stability of their hibernation.
It would be great to see Hikari and Kaname wake up first, but now having Miuna and Sayu behigh schoolersmiddle schoolers in the same year. Then you'd have Chisaki wake up a few months after to make a mess of things. Manaka would stay asleep. The downside to that would be that it would be really unfair to Tsumugu, but honestly I'm not sure he really cares about Manaka that way. Then again, there's been plenty of romances with a large age gap, even in this series. Akari is much younger than her soon-to-be husband.
Side note: I'm really starting to like Sayu's character, when I used to find her annoying. She dresses rather femininely when compared to Miuna, and is certainly a little more emotionally mature than her as well (because she knows she wants Kaname, just describes it as being "evil" instead of being in love, hah).
Despite that, she's a huge tomboy. She headbutted Hikari's father...