In the dangerous suburbs of Chicago, skilled bounty hunters Irene "Rally" Vincent and "Minnie" May Hopkins run Gunsmith Cats, a firearms store of questionable legality. One day, Bill Collins, an agent for the Chicago branch of the Bureau of Alcohol, Tobacco, Firearms, and Explosives, blackmails Rally and May into working with him on a case. The stakes are high, but Rally’s gunmanship and May’s knowledge of explosives are unmatched. As Rally and May unravel the secrets of the case, the two will need to use guns and grenades while being faster, stronger, and better than everyone else in order to stay alive.

Following the massive operation that led to the confinement of recent recruit Kafka Hibino, otherwise known as Kaijuu No. 8, the Defense Force has been puzzled by how to deal with him. Kafka is the first kaijuu to side with humans, and after careful consideration, he is eventually transferred to the Defense Force's First Division in the hope of adding his power to the strongest division, capable of handling any threat. However, some people are still doubtful about Kafka, and he must prove his worth in the next mission. Kafka and the First Division are soon dispatched when a massive horde of ant-like kaijuu begins wreaking havoc. Thanks to the combined strength of Kafka's friend Kikoru Shinomiya and their captain, Gen Narumi, the mission seems to progress as it should. However, when Kafka fails to transform into his kaijuu form, the dreadful Kaijuu No. 9 joins the battle with only one goal—to eliminate him and steal his power. Although the situation is looking grim, Kafka must overcome his most difficult trial yet with the others if he wants to keep pursuing his dream: fighting side by side with his childhood friend and Third Division captain, Mina Ashiro.

There have been many cases of stolen songs happening among the idols in Yokohama District recently. Even super idol Marine Amagi's hit song "Kiseki no Uta" was taken away. At the request of Marine, the Milky Holmes team starts investigating the case.

It is said that fireworks can calm the souls of the dead. For Tomoya Sugisaki, Aoi Harukawa, and Ryou Kobayashi, fireworks are what allowed them to meet the Summer Ghost. Believed to be the spirit of a young woman who committed suicide, the Summer Ghost only appears in a specific area and can only be seen by those who are within arm's reach of death. Tomoya is a creative soul being crushed by his academic obligation to get into a good university. Aoi is a meek girl who is relentlessly bullied by her classmates. Ryou is a former basketball star who had to forfeit his passion following a grim diagnosis. The only thing these three have in common is their ability to see the Summer Ghost. The Summer Ghost is said to be able to answer any and all questions pertaining to death—something the three teenagers desperately want to know more about. Dissatisfied with their initial meeting, Tomoya sets out to find the Summer Ghost once again. But the more time he spends with the ghost, the more the mystery surrounding her existence unravels.