To get the Special Ending You have to pick these Characters.

Kyo-Shingo-(and anybody else except Iori)
Kyo-Iori-Chizuru
Kyo-Mai-Billy
Kyo-Terry-Ryo
Mai-King-Yuri
Yamazaki-Choi-Chang
Terry-Mary-Joe
Kim-Benimaru-Joe
Ralf-Clark-Athena