Costantini was born on 31 January 1918 in Castel d'Aiano, son of Giovanni and Florinda Fini. After completing his primary education, he began working and distinguished himself for his athletic abilities as a marathon runner. He served in the navy in Messina from 15 February 1938 to 21 April 1938, after which he was discharged due to physical problems.

He was employed by the railways in 1941 and was living in Vergato in 1943. After the armistice, he hid weapons and was consequently imprisoned and dismissed for subversive activities. In the early months of 1944, several young men from Vergato went into hiding, joining the Red Star partisan brigade before forming, in June, an autonomous unit led by Gino, who took the nom de guerre ‘John’. This unit later joined the Modena Armando Garibaldi Division, whilst continuing to operate in the mountains between Calvenzano, Vergato and Labante.

In October and November, the German command ordered the evacuation of a large portion of territory close to the front line, including Vergato. It became risky for the partisans to continue operating and, in agreement with their command, Costantini’s unit crossed the front lines, reaching the Allies at Castel di Casio and joining them on the front line at Oreglia.

After January 1945, the unit took the name ‘Pilota’, after the nom de guerre of one of its fallen comrades, Dario Pedrini, and was incorporated into the Selvino Folloni Brigade of the Modena Armando Division.

’John’s‘ men fought in ‘no man’s land’ alongside the Allies, first the South African troops and then the American ones, until spring 1945. On 5 March 1945, after fierce fighting, the Brazilians entered Castelnuovo. Vergato, the district capital, was liberated on 16 April. Gino was recognised as a partisan with the rank of lieutenant from 17 June 1944 to 30 April 1945. At the end of the war, he was re-employed by the railways, where he remained until his retirement. He lived in Vergato, serving as president of the local branch of the ANPI.

In 2002, he welcomed the President of the Republic, Carlo Azeglio Ciampi, to the village, who awarded Vergato the Gold Medal for Civil Merit for the suffering endured during the numerous bombings and for the solidarity shown towards the displaced.

In 2010, Gino published his autobiography, Courage Cannot Be Bought. He died on 27 December 2013. He is buried in the cemetery at Calvenzano.