It is the year 2004 AD, and pandemonium breaks as a mysterious frog-like alien race fills the sky with UFOs—or so 12-year-old Fuyuki Hinata dreams. Coincidentally, Sergeant Keroro, leader of a preliminary squad for the Keronian invasion of Pekopon—the alien name for Earth—begins his mission by invading Fuyuki's home. After subduing the boy and his sister, Keroro plans to reunite with his comrades and return to the mothership to repair his invaluable invasion device, the Kero Ball. Unfortunately, he receives word that headquarters has abandoned his unit's retrieval due to an unprecedented issue that forced the rest of the Keronians to flee. Consequently, Keroro is forced to stay at the Hinata residence together with the friendly, starry-eyed Fuyuki; his athletic, short-tempered sister Natsumi; and their hardworking, attractive mother Aki. Now stuck until further notice, Keroro and his platoon spend each day plotting world domination, but are thwarted each and every time by various unexpected factors. Nevertheless, as they live alongside humans, they learn to treat them as friends and allies, forming comedic yet meaningful connections that make their lives on Earth worthwhile.

Rikka Isurugi has spent her life training in the way of the ninja with her grandfather Hyoe while following in the footsteps of her father, the esteemed researcher Allen. His work has culminated in a set of cutting- edge drones equipped with artificial intelligence and incredible technical capabilities; although Allen plans to develop these drones for civilian use, there are others who have more sinister ideas in mind. On Rikka's 16th birthday, things are forever changed when a paramilitary group raids the Isurugi house in search of the drone technology, killing Allen and Hyoe while Rikka manages to escape with the drones. Months pass, and Rikka is now an ordinary girl working as a private detective while sharing an apartment with another girl, Melissa. But when night falls, she dons her grandfather's fox mask and mercilessly hunts down those responsible for the attack. With the anger she felt that day driving her forward, Rikka will not rest until her family's killers receive the justice that they deserve.

At Arkham Asylum, Batman clashes with Gorilla Grodd while trying to destroy Grodd's newest invention: the Quake Engine. Amidst the chaos, the engine activates, and the entire asylum suddenly vanishes into thin air—Batman along with it. Once the dust settles, Batman finds himself standing in the middle of an unfamiliar road. He soon realizes that he is no longer in Gotham City—but instead in Feudal Japan! The amazement quickly fades as samurai descend upon him, seeking to take his life. Later on, Batman's investigation leads him to discover that the one responsible for the kill order is none other than his archnemesis, the Joker. Following an encounter with Catwoman, he learns that the asylum's criminals had teleported there two years earlier—each ruling over a piece of Japan with Joker being the dominant warlord. In order to return home, Batman must reactivate the Quake Engine, situated in the remnants of the asylum, now known as Arkham Castle. However, there is one problem: aside from his gadget belt, the arsenal that was once at his fingertips is all but gone. Ninja Batman follows the Dark Knight as he traverses a strange new environment, facing off against familiar foes in a bid to return to Gotham in one piece.

Despite being one of Zebrudia's few level 8 treasure hunters and the leader of the capital's top party, Grieving Souls, Krai Andrey does not deserve his prominent reputation. Everything he says somehow turns prophetic, which convinces everyone around him that he possesses unfathomable wisdom regardless of his utter incompetence. Krai knows his success is only a series of coincidences, but the weight of those expectations grows heavier as time goes by. Unfortunately, as the other members of the Grieving Souls continue to shock the world with their achievements, Krai's wish for a peaceful retirement drifts ever further out of reach.