This Cyril's universe is a crossover with the manga Olimpos by Aki! There is no wiki about it (pretty small manga, sob), so here's a terrible summary:
Heinz was just an ordinary man looking for some way to win over his love and gain success. Desperate, he began to pray to God, saying that he would do anything to somehow succeed (though he never meant this). Hearing his prayers, 'God' appeared before Heinz and told him that he would grant his wish, kissing the man before whisking him away to a silent land of flowers.
"If you can get the boy here to leave, I'll grant your wish," said God.
Heinz, thinking that this would be an easy task, agreed to doing it and set out to find him.
Of course, it wasn't that easy. The boy was so convinced that he could never leave that he cut off his own arm to stop Heinz from taking him. The god who had appeared before Heinz had tricked him into doing a seemingly easy task.
Heinz despaired.
So, I've only read up to about chapter 3, but I know some of the characters in this manga. There are three main Gods who show up: Apollo (who appeared before Heinz), Poseidon, and Hades. And of course, there's Ganymede and poor Heinz. I also believe there's a girl named Iris and the goddess Artemis.
Cast list will go on the next post!
ALSO: I apologize if my knowledge of this manga seems very little, and it is. I have only been able to read the first three translated chapters since I cannot read Japanese (sadly), and I don't know what else happens in this manga. If you want or need to read these chapters in order to understand the canon, you can read the three translated chapters
here. I think that there are a few raw versions or chapters 6 and up floating around out there, but I'm not entirely sure.