Below is a list of hidden characters with descriptions of what you must do to unlock them. Note: characters with an asterisk (*) next to their names are normally villains or anti-heroes.

Character	How to unlock
Big One	Accept to cooperate with the JAKQ Blitzkrieg Squad in Chapter ID 042; Big One will join your party from Chapter ID 044.
Bijinder*	Accept to cooperate with Kikaider 01 in Chapter ID 032, then complete Chapter ID 034 with Kikaider and/or Kikaider 01 in your party.
Biorider	Start the game with Kamen Rider Ichigou. Have Kamen Rider Black RX in your party for Chapter ID 090.
Bishoujo Kamen Poitrine	Complete hidden Chapter ID 046 (unlocked by achieving a Rate of Evil of 75% or less after the completion of the second set of scenarios).
Garagaranda*	Start the game with Kamen Rider Ichigou, then complete Chapter ID 004 without Kamen Rider Ichigou in your party.
Inazuman F	Accept to cooperate with Inazuman in Chapter ID 094; Inazuman will evolve into Inazuman Flash in Chapter ID 098.
Kamen Rider Black	Start the game with Kamen Rider Ichigou; Black will join your party from Chapter ID 080.
Kamen Rider Black RX	Start the game with Kamen Rider Ichigou; Black will evolve into Black RX in Chapter ID 088.
Kamen Rider Nigou	Start the game with Kamen Rider Ichigou; Nigou will join your party from Chapter ID 006.
Kamen Rider ZX	Complete hidden Chapter ID 048 (unlocked by achieving a Rate of Evil of 47% or less after the completion of the fourth set of scenarios).
Kujira Kaijin*	Start the game with Kamen Rider Ichigou, then complete Chapter ID 083 with Kamen Rider Black in your party.
Machine Man	Complete hidden Chapter ID 116 (unlocked by achieving a Rate of Evil of 58% or less after the completion of the third set of scenarios).
Mogura Juujin*	Accept to cooperate with Kamen Rider Amazon in Chapter ID 075, then complete Chapter ID 076 with Amazon in your party and choose to help Mogura.
Power-up K	Accept to cooperate with Robot Detective K in Chapter ID 028, then complete Chapter ID 030 with K in your party.
Riderman	Accept to cooperate with Kamen Rider V3 in Chapter ID 007, then complete Chapter ID 011 and don't have Riderman board the rocket during the mission.
Robocon	Complete hidden Chapter ID 047 (unlocked by achieving a Rate of Evil of 85% or less after the completion of the first set of scenarios).
Roborider	Start the game with Kamen Rider Ichigou. Have Kamen Rider Black RX in your party for Chapter ID 089.
Rose Bambara*	Accept to cooperate with Inazuman in Chapter ID 094, then complete Chapter ID 095 with Sanagiman in your party.
Shadowmoon*	Start the game with Kamen Rider Ichigou. In Chapter ID 084, don't pick up the Satan Saber; Shadowmoon will join your party from Chapter ID 088.
Tsukinowa	Accept to cooperate with Henshin Ninja Arashi in Chapter ID 018, then complete Chapter ID 022 without Arashi in your party.
Walder*	Accept to cooperate with Kikaider 01 in Chapter ID 032, then complete Chapter ID 036 with Kikaider and/or Kikaider 01 in your party.