By the end of the game, Palm has come to learn that not only was Larsa manipulating Aki, but that Reco had been trying to save Aki rather than destroy him. One of Larsa's other sons, Palm, sets off to find Reco, seeking the truth behind his brother Aki's demise. Larsa, having heard of Aki's death, becomes enraged and obsessed with killing Reco. Picking up immediately afterwards, Mushihimesama Futari tells the story of Reco and Queen Larsa, the mother of Aki from the original game. However it is the boy, Aki, acting as the king of the Koujuu whom Reco must destroy at the end of the first game in order to save her people. Presumably it is this imbalance that has caused the people to die. The reason for this pestilence as it is revealed at the end of the game is that a young boy she met in her youth bestowed upon her a bracelet that protects from the ill effects of Levi-Sense. In the original game, Princess Reco, who is 15, is sent to speak with the Koujuu king after her people begin to die from Levi-Sense poisoning. In an agreement, small pockets of humanity are allowed to live in exchange for the sacrifice of a 15-year old girl every 200 years. The world of Mushihimesama is primarily inhabited by large arthropods (insects, crabs, etc.) called the "Koujuu" that give off a life-force known as "Levi-Sense" that is fatally poisonous to humans. Mushihimesama Futari is the sequel to Mushihimesama, and continues the story from the original game. It is essentially provided to give the merest sense of context for the game's setting and the actions of the characters. While not particularly common in a game of this type, Mushihimesama Futari and its predecessor do contain something of a bare-minimum plot line.
The port is generally well-received, being in general very accurate to the arcade version of the game, and also for including access to the Black Label version as DLC. (CAVE ultimately did release a few subsequent Xbox 360 shooters in region-free format, including Espgaluda II Black Label and Muchi Muchi Pork! & Pink Sweets.)
CAVE's Makoto Asada cited heavy support from overseas fans as the reason for this decision, and also stated that how well non-Japanese sales performed would determine whether CAVE would make region free or seek licensing for future CAVE ports. While the Xbox 360 port of was only released in Japan, it was released without a region lock, allowing the game to be played on non-Japanese consoles: the first Japanese-exclusive Xbox 360 game to do so. Originally released in arcades in 2006, Futari is often recognized as one of the most difficult single-loop shooters in existence when played on its hardest difficulty setting. Mushihimesama Futari is the sequel to another popular CAVE bullet-hell shooter, Mushihimesama.