In the aftermath of a great and terrible war, Haruka finds herself the last surviving human on Earth. Though humanity may have been wiped out, she is not entirely alone. Advanced robots have survived the apocalypse, and Haruka lives with five who care for her: Spike, a boyish android who is very attached to her; Trigger, hot-tempered with a penchant for firearms; Cleric, the intelligent problem solver; Reeves, whose thoughtfulness overshadows his intimidating appearance; and Angela, a sword wielding recluse with an aversion towards humans. Residing in a high-rise building at the center of the city, Haruka lives a relatively peaceful life with her mechanical family. However, her life is far from a stable one. Not only is a lack of resources a concern, but violent, remnant robots from the war roam free, ready to destroy whomever they meet. Kurogane Communication follows Haruka as she tries to survive in an apocalyptic world while facing many dangers that will challenge her daily life.

Sasahara Natsuki is a poor bounty hunter in a world where monsters and humans live together. Most of her cases involve monsters infringing upon the rights of humans, who are protected by law from their generally more powerful neighbors. Being half-human and half cat-beast, Natsuki straddles the two societies and tries to understand and respect both while enforcing the law. She is assisted by a werewolf named Batanen who is afraid to admit he loves her; another werewolf named Tommy; and a Kyubi fox demon named Sakura who has her own plans--which include eating Natsuki to complete her her nine tails and thereby her magical powers.

Once every century, the legendary mahjong dials called the "Legendary Pai" show themselves to the world, and if you collect them all it will grant you any wish. They show up in the form of evil monsters and you must defeat all 10 to obtain this chance. So, a Bunny Alien, A Maid-Dominatrix, A Cyborg, A girl form the world of magic and a transforming super hero all must fight these monsters along with themselves to grant the wish that they want to come true.