Cozzato first met Giotto and G when they returned his wallet that he purposely dropped to help their poor neighbor, Paolo, since he knew that Paolo's master didn't treat him and his family well. Hearing this, Giotto revealed that they also dropped the same amount of money for Paolo to take, making Cozzato laughed. They introduced themselves, starting their friendship. One day, when Franco, one of their friends, was attacked by group of thugs for refusing to give them 90% discount and no doctors are helping him due to being threatened, Cozzato suggested to make a vigilante group to protect the townspeople from outlaws and pointed Giotto to become the leader, creating Vongola Famiglia.
Several years later, Cozzato received letter from Giotto that expressed his fear that the Vongola he originally created would bring harm due to the great power they have. At the last part of the letter, it was informed that there'll be a big war coming up and ask for his assistance. Realizing that the last part of the letter was fake since it was addressed as "from Vongola Primo", Cozzato went to help Giotto in the war. During the war, he was approached by Demon Spade's subordinates who offered them their help. However, Cozzato already knew that Demon was actually intend to kill him and his Famiglia. At this, Demon Spade's subordinates revealed themselves as G and the other remaining Guardians who had been ordered by Giotto to save him since he had seen through Demon Spade's plan.
Afterwards, he, Giotto, and G met up and discussed what should they do with Demon. Cozzato suggested that they should kept his and his Famiglia's survival a secret as he had a strong feeling that getting rid of Demon won't be an easy task and decided that he and his Famiglia would live in the shadow. Giotto at first reluctant, but seeing Cozzato won't back down, he agreed under condition that the Simon would always help Vongola from the shadow as long as the Famiglia exist, which Cozzato wholeheartedly agreed. With the vow had been made, an Arcobaleno with clear pacifier and a Vindice, Bermuda von Veckenschtein and Jaeger, appeared in front of them, declaring they shall imprison those who lost the battle if the Vongola and Simon ever crossed sword against each other as this is also part of Mafia law.
Since then, Cozzato and his Famiglia lived isolated in Simon Island and never met either Giotto or Vongola again for the rest of their lifetimes, but both confident that one day their true descendants who bear their wills will meet and smile together again like they did. After his death, he was buried in some part of the island along with Simon Rings within his tomb.
Throughout the battles between Vongola and Simon and Demon Spade, the Vindice granted the two Famiglias seven keys that shows Cozzato's memory Giotto as well as the true history behind Simon Famiglia's isolation after each battle occurred.