In the NTSC-J version, the character on the game's box art has more revealing cleavage than on the NTSC-U version. The box art was changed for the NTSC-U version so that her chest is more covered.

In Japan, the game is titled Planet Destroyer Black Heart.

All supporting characters are reference to other game franchises:

• Vio - Resident Evil
• Moru - Monster Hunter
• Lee-fi - Street Fighter's Chun-Li.
• Lid - Metal Gear Solid's Snake
• Wyn - Soccer games, possibly Winning Eleven by Konami.
• Saori - Tokimeki Memorial's Shiori Fujisaki
• Restra - Record of Agarest's Ellis
• Little Rain - Neverland
• Generia · G - Gundam Generation
• Lady Wac - Pac-Man
• Ai Masujima - The Idolmaster
• Estelle - Dragon Quest 3's male hero
• Ein Al - Final Fantasy
• Sango - Dynasty Warriors' Sun Shang Xiang
• Poona - Opuuna.
• Blossom Aisen - Sakura Wars
• Ryuka - Yakuza
• Tsunemi - Vocaloid's Hatsune Miku

Additionally, the DLC character Sting represents the developers of the game, also called Sting.
The DLC character Tiara is a cameo from Compile Hearts' Fairy Fencer F.