J. Olloqui is the old guy who wrote this book. He's over 30. He loves popular literature, the cinema, comics, and pop music - and that's why he's always in a bad mood. Although he took up writing at an early age, when he was a teenager, he took a detour from the world of letters to discover pop. That was when he decided he didn't want to be a writer anymore but a rockstar, because rockstars have more friends (which is false, they have the same number of friends, that is, none). He has recorded and produced records, and he's played with several groups although none have been as famous as Yumi's. He has written stories and articles on different media. He has also published novels: "¡Malditos terrícolas!" (Naughty Earthlings) and "Betamax, una comedia con superpoderes" (Betamax, a Comedy with Superpowers). "Yumi y su banda" (Yumi and His Band) is his series of books for kids with style and adults who have decided never to do something as stupid as grow up.