Let's get this straight out before people go and yell about it. Yes, this story has a story that had potentially not so healthy relations between a high school boy and a person a bit too young.
The story is of high school student council president who believes he is an Alpha. Ironically it is discovered he is in fact an omega. Yes, once again, we're in the omegaverse. Chika, the unfortunate Omega, is now attracted to Haruka, an Alpha far too young and yet his chosen pair. The story covers Chika being near Haruka to the point where they must be apart for a bit longer in order to... well... be somewhat tasteful? Either way, the story progresses as tastefully as it can try. It's not the best, but it does what it does better than some other stories.
Your typically really good art. At least this time it's not on a bad story and the characters really do look distinct. I'm glad for that, since... It'd be hard to know who everyone is if they didn't. It doesn't cut corners too much and it keeps it up to the end.
These vary based on their involvement. The main couple is well developed, though I do have to wonder why Chika would endanger his findings sometimes. Haruka does his best, but in all honesty he probably is the best when he's finally old enough to do something properly. As for the supporting, the female student council member is probably the one who stands out the most. Hazawara is probably the omega that stands out the most for simply being the one who stays close to Chika, even if it might have been more beneficial for her not to. The others vary from not being vary helpful to... well, just sort of being there.
Overall, the story for Sayanora Alpha is probably one of the better Omegaverse.