Vertigo, I noticed that I had one grey message marked as ??? when I continute my save on 0.32.0. Was it on purpose or I missed something that will unluck it? Please let me know if it's on purpose so I woundn't take days wonder where I did wrong. ;)
The message is from Tsubaki, the green-haired girl from the track & field club. You have to pick her as your favorite at the track to get her number/give her your number, and thus be able to get a message from her.
Quick disclaimer, though: It's a rather short message interaction for now. There will be more in the future, based on this, but yeah. May or may not be worth going through the trouble of going back to that decision just to see it. :)