"27-year old single man"
I... don't see a single trace of this. It's like he was a teenager in an adult's body from the start and so not much really changed for him.
So Nanaya says he regrets not letting her know how he feels, but it's looking more like he's going to waste his time and second chance all over again by being the same coward unable to confess. On page 32 was a chance to come clean and confess, but of course he won't and didn't. Don't tell me he relives these 11 years again and only confess when he's 27 again for the ending. I want to believe he'll develop out of this cowardly self, but so far he isn't very convincing...
Well, at least now it's confirmed Touka has her adult memories too. They both time leaped into the past. This fact just saved this manga for me, as it should be interesting. We haven't even gotten to confirming the possibility that others also have their adulthood memories and that also has potential.