"We called him Bambi because of his doe-like black eyes and long, full eyelashes," she told La Repubblica newspaper, which gave her an assumed name, Murielle, to protect her privacy.
"We went to the disco together every Saturday afternoon. He had a fixation with America, it was his dream - the music, hip-hop.
"He dressed like a rapper in baggy trousers and basketball T-shirts. He drank alcohol, beer, he danced really well," she recalled.
"Murielle," now aged 26, said she met the Ethiopian, also known as Hamdi Isaac, a decade ago among a crowd of teenage friends who used to hang out each afternoon after school on and around the walls next to Rome's Piazzale Flaminia square at the edge of the Villa Borghese park.
"He was not a suspicious character. I got a shock when I saw him on television," she said.
"My best friend introduced me to some friends of his. It was hard not to notice Hamdi because he was kind as well as good looking - the photographs handed out to the media don't do him justice." Before leaving Italy to seek asylum in Britain, Mr Osman gave few signs he would drift into the world of Osama Bin Laden's recruits, she added.
"He worshipped American rappers, Tupac, the Afro-American ghetto culture of the Bronx. He and his friends added the letter "g'' to the end of their names, "g" for gangster, or rather "gangsta" as in "Gangsta Paradise," a successful song at the time but Hamdi was not a violent person.
"He was a good person, he never mixed in bad company. If there was ever a brawl where we hung out he would always be a peacemaker. He enjoyed picking up girls, that is true, in that sense his religion didn't seem to get in his way.
"We knew he was a Muslim but he never talked to me about that, he had no problem going out with us non-Muslims ... friends who saw him in London two years later told me he forced his partner to wear a veil.
"Some said she was an Eritrean Christian he had convinced to convert. He used to come to Rome for holidays every now and again and we would see each other."
She added: "He went to London to obtain political asylum. In fact, I had to address my letters to a new name. In Rome he wasn't able to achieve anything whereas he said in London there was more to do.
"Basically he wanted to have fun, which is why it still seems strange that he should end up on the Tube with a fake bomb."Reuse content