Mystery of Soft Machine (ソフト・マシーンの謎 Sofuto Mashīn no Nazo) is the fifth story arc in Vento Aureo.
It narrates the ambush of Bucciarati's Gang by an unknown Stand as they head to Capri to retrieve the late Polpo's treasure and the investigations of Bruno Bucciarati and Leone Abbacchio with the aid of Abbacchio's Moody Blues.
Narancia, Mista and Fugo disappear after an attack by a hidden assailant. Giorno volunteers to be attacked; is stabbed by an arm emerging from the lower deck, and then deflated like a balloon. Abbacchio activates his Stand Moody Blues, replaying Narancia's history and revealing that Narancia was deflated.
- 03 (49). Find Polpo's Fortune!