Astro Boy: Omega Factor (GBA)

Unlock Sharaku Hosuke
Successfully complete the game two times and wait after the credits complete for a sequence that unlocks Sharaku Hosuke as a selectable character.

Unlock Stage Select Mode
Unlocks the stage select option from the pause menu. Astro Boy can still build up his stats and even meet new characters. You have to Beat the game in normal mode.

Completion Bonuses
Successfully complete the game to unlock options for stage select, sound test, and event test. Successfully complete the game two times and wait after the credits complete for a sequence that unlocks Sharaku Hosuke as a selectable character.