Nathaniel Shani was found with knife injuries by emergency services in Tavistock Square, Harpurhey, shortly after 6pm on Friday.
He was taken to hospital but his injuries were so sever he died.
A 14-year-old boy was arrested shortly after the incident on suspicion of murder and remains in custody.
In an update on Saturday, Greater Manchester Police said a 13-year-old boy has also been arrested on suspicion of murder.
Paying tribute to the victim his family said: “Nathaniel was a best friend to many, he never failed to make people laugh. Nathaniel was very kind, caring and always thinking of others.
“He was polite and the most loving person. He would always put other people first without a thought. He was an amazing brother and son to his parents and siblings.
“Our hearts are left broken. Rest in paradise to the most kindest soul.”
Detective Superintendent Rebecca Boyce said: “This incident that has seen a young boy sadly die has understandably rocked the local community in Harpurhey.
“We now want to appeal to the local community for any eyewitness accounts or footage of any activity that we may be able to link to this investigation.
“It is crucial we have as much detail as possible to help piece together what has happened in this tragic incident where someone has sadly lost their life.”
Anyone with information is asked to Call Greater Manchester Police’s Major Incident Team direct on 0161 856 3015 or 101 quoting incident number 2843 of 15/09/2023 or to remain anonymous Crimestoppers on 0800 555 111.