"Green Day" and "Oasis" (4) (『グリーン・ディ』と『オアシス』 その④ "Gurīn Dei" to "Oashisu" Sono 4), originally A Simple Question! (素朴な疑問！ Soboku na Gimon!) in the WSJ release, is the five hundred fifty-seventh chapter of the JoJo's Bizarre Adventure manga. It is also the one hundred eighteenth chapter of Vento Aureo.
Bucciarati pummels Secco violently, forcing the Passione member to hastily retreat underground and call Cioccolata. Secco asks his master if Green Day works on dead flesh, as he touched Bucciarati and it was deathly cold, but Cioccolata doesn't know the answer. The surgeon sees Bucciarati's group escaping the village in a car, confusing him as to how they could have defeated their combination.
In the car, Mista is impressed that Bucciarati jumped down and asks how he could resist the mold. Giorno, out of the turtle, changes the conversation subject and tells Mista to rest a little. Giorno tries to heal Bucciarati, but touching him, realizes that he's too cold to be living; Bucciarati admits that for unknown reasons, he's living on borrowed time and asks Giorno not to tell anyone. Their conversation is interrupted when a mold-ridden corpse crashes into the car.