We propose to measure three parts of a full suit of armour pertaining to the Stibbert Museum in Florence (Italy) which recent studies on leather and fabric components of it, evidenced the high probability that it might have been worn by one of the generals participating to the Shimabara battle in 1636 which has been one of the most historical-political events in Japan. This armour is for sure a high quality piece with high quality metallurgical properties since it present several bullet deformation in many of its parts. The aim of the measurement is to determine the average carbon content by the ratio between cementite and ferrite phases in selected parts of the three components in order to confirm the common provenance and the probable Indian origin of the raw material.