Beat Story on Medium or Hard with Shinobu without continuing.
Ichiko
Obtain 14 wins in Survival mode after unlocking Tetsuko & Genichiro.
Play as Shinobu
Choose a difficulty of two or three stars and finish the game without using any continues. Fight Shinobu to complete the game. Then, go to Vs. mode and press R1 or R2 to play as her.
Secret character
Quickly press [Up(2), Down(2), Left, Right, Left, Right, X, Circle] three times after hearing "Suta Ato, Oshite ne" spoken. If you entered the code correctly, you will hear a clashing sound. Then, enter the character selection screen (not story mode), and press R1.
Tetsuko
Beat Story on Medium or Hard with Asuka or Karina without continuing.