In the near future, civilization has collapsed, and the world has become a wasteland. Despite their poverty, the people use remnants of past civilizations to lead resilient lives. Gear works in a junk shop while also retrieving stolen goods alongside Qu-0213, a robot with four personalities, and White Bear, a gambler. One day, Gear finds himself thrust into a once-in-a-lifetime job to steal an important item. They soon find themselves up against deadly assassins, heart- pounding car chases, and explosive battles. What Gear and his team do not know yet is that the item they stole holds a secret that could shake the very foundation of this world.

Robotic invaders wiped out all life, but Renge fights to survive using her powers. With no memories, she roams the city until she meets five other young women, each with unique abilities. Together, they make the most of their lives, cooking delicious meals between battles with mechanical monstrosities. As they uncover the secrets of their powers and pasts, they find strength in their friendship.

The protagonists of the series are the three Kisugi sisters—Hitomi, Rui and Ai—who run a café called Cat's Eye. The sisters lead a double life as a trio of highly skilled art thieves, leaving cards with the name "Cat's Eye" at the scene of their crimes. They steal works of art that belonged to their long-missing father, Heinz who was a famous art collector during the Nazi regime, in the hopes of him contacting them. Toshio, the police officer investigating this case is the fiancé of Hitomi. He also swears to capture and bring down the Cat's Eye Gang.

Situated within an endless twilight, the Tasogare Hotel welcomes anyone stuck between life and death. Unaware of their fate, guests must regain lost memories through mementos hidden in their designated hotel room. Most guests pass on or return to the world of living within days, while few others find themselves staying at the hotel for much longer than usual. Neko Tsukahara, a young woman with an expressionless face, finds herself at this hotel. As she is guided along by the staff, Neko regains enough of her memories to become invested in the plights of the other guests. Solving the guests' affairs and the mystery behind the hotel turns out to be too interesting of a situation to pass up; Neko decides that simply being a guest is not enough to satisfy her curiosity.