Over at Néojaponisme, I am determined to solve this V-sign thing once and for all. Any who can better my information, I choose you!

A3a. V-sign for “Victory” (Japan, pre-Bubble): Enters popular consciousness in late 1960s via baseball manga/anime Kyojin no Hoshi 『巨人の星』 ("Star of the Giants"). Hero Hyūma believes father has not come to say goodbye at train station as he departs for Kōshien, but father appears at last moment and throws up V. Hyūma recognizes it as "the V-sign of victory!" ("Shōri no V-sain!") and resolves to win.