Enable special options:
Press A, B, C, B, C, B, A, Start at the title screen after the text "Press Start" appears. A special options selection will now appear in the main menu. Use this option to view or listen to the graphics, sounds and music tracks.

Unlock Voice Dramas:
Highlight "Omake" on the main menu. Hold L + X + Z and press C.

Voice drama background selection:
Highlight a Voice Drama title, hold C, and press one of the following codes.

Background graphic	Code
Maki and Megumi surrounded by "deformed" versions of the other girls	L + Start
Maki in a tux and Megumi in a dress.	L + X + Start
Maki wearing gloves and Megumi holding a naginata.	L + X + Y + Start
Maina, Maki, Mami-chan, and Megumi in foreground, Kiyomi-san, Shizuka, and Yurika in background.	L + X + Y + Z + Start
Kiyomi-san, Mami-chan, Mika, Reiko-sama, and Shizuka in foreground, Maina and Yurika in background.	L + X + Z + Start
Cindy, Kiyomi-san, Mika, Misako, and Yurika.	L + Y + Start
Maina, Mami-chan, Reiko-sama, Saori, and Shizuka.	L + Y + Z + Start
Cindy, Maki, Megumi, Misako, and Saori all dressed in sailor fuku.	L + Z + Start