Hoshino won by armbar over Takeshi Yamazaki at 3:23 of the third round, while Nishiura and Oishi won unanimous decisions over Fanjin Son and Tetsu Suzuki, respectively.
Nishiura and Hoshino will face each other in the finals of Cage Force's 145-pound tournament.
Oishi will fight in the finals of the 135-pound tournament against the winner of the Nov. 8 bout between Takeya Mizugaki and Taiyo Nakahara.
Cage Force, formerly known as Demolition of Octagon Gear (D.O.G.), is the only cage fighting event in Japan.
145 lbs. | Yuji Hoshino def. Takeshi Yamazaki via submission (armbar) - R3 (3:23)
145 lbs. | Akiyo "Wicky" Nishiura def. Fanjin Son via unanimous decision
135 lbs. | Masahiro Oishi def. Tetsu Suzuki via unanimous decision
155 lbs. | Yoshihiro Koyama def. Bum-Chang Kang via TKO (strikes) - R1 (3:35)
135 lbs. | Takeya Mizugaki def. Daisuke Endo via submission (RNC) - R1 (4:34)
145 lbs. | Wataru Miki and Tomohiko Hori went to a draw
170 lbs. | Daisuke Okumiya def. Tetsuo Seto via TKO (doctor stoppage) - R1 (5:00)
135 lbs. | Yuta Nezu def. Ryo Taguchi via KO - R1 (0:36)
155 lbs. | Daisuke Hoshino def. Junichi Ota via unanimous decision