Review of Sing "Yesterday" for Me

Uff. I really had my hopes in this one as my new favorite anime. At first, we have some very good written characters that can develop a lot while times pass. Rikuo was forced to grow up even that he wasn't prepared, he had a complex and secret personality, he used to run away from pain and never face up the things. And that is for me an interesting main character to a slice of life, romance, drama like this one. Then we have Haru who is mature but childish at the same time, similar to Rikuo, she runs away but also hates doing it"maybe I don't have any other places to run" (at least in Spanish she said something like that).

Shinako was different in some ways, she tried to move and become a teacher as she wanted, but had a big problem in the past that stopped her from a lot of things like loving someone.

Finally, Rou who was... more childish with his emotions and actions but it's ok, I don't blame him.. he has some troubles in the past and even present.

They were very careful in their presentation, wanting to share a good impression so they used to hide a lot of their problems and not being honest with themselves either but trying to do it as a process would be in real life (maybe with some therapy)

Not the best explanation of the character but it's something.
They had a lot of potentials that in my opinion wasn't really exploded, I´m assuming that it´s because it's 12 episodes long but even then...
The whole plot its that four or three characters and how they grow up, entering the adult life and loving if you can´t show us that properly maybe you should wait a bit longer.
Please don´t get me wrong, I actually liked it, but my expectations were so high up that I expected something a lot better because this anime could give us that.

I don´t wanna spoil anything but THE END WAS SO GODDAMN FAST... That's it. thx for reading.
Ps: I'm gonna read the manga hoping to read a better ending and development; also for good fanservice