JJ is played by Riccardo Frascari, who is from Italy in real life. Riccardo also dubs JJ's lines in the Italian version of the show.
JJ grew up in Italy, where his father owns a pizza shop. After moving to Manzanares, he meets and falls in love with the time traveller Eva. When JJ needs to return to Italy, he has a hard time parting with Eva, but thankfully they reunite a few episodes after.
"JJ has a big heart, a lot of talent, and is very funny. He has a rebellious and selfless attitude, which sometimes hinders his aspirations. But everything changes when Eva arrives and tells him to follow his dreams." — MundoNick.com