Yakumo Fujii (藤井 八雲) is the primary male protagonist of the 3x3 Eyes series.
He became Pai Ayanokoji's Wu and companion when a rampaging Takuhi, Pai's demon friend, fatally wounded him. Before he could die, Pai merged his soul with her own, transforming him into a Wu, which in turn made him immortal as long as Pai lives. He can feel pain but he won't die. He will regenerate from any wound, no matter how severe.
His father, Professor Fujii made a promise to help Pai become human before he died and Yakumo tries to keep that promise. Yakumo has been shown to have feelings for Pai.