A top agent from the devil's training camp was shot and killed by her superior's mutiny. However, she is reborn and becomes the powerful third young lady of the Yan family who is escaping from the extermination……

After the destruction of their hometown, childhood friends Kafka Hibino and Mina Ashiro make a pact to become officers in the Defense Force—a militarized organization tasked with protecting Japan from colossal monsters known as "kaijuu." Decades later, the 32-year-old Kafka has all but given up on his dreams of heroism. Instead, he cleans up the remains of the slaughtered kaijuu after they are defeated by valiant soldiers—including Mina, who has successfully achieved their shared goal. Upon meeting his new coworker, Reno Ichikawa, Kafka faces a mirror of his past self: an ambitious young man whose one desire is to fight as a member of the Defense Force. Unfortunately, the two are soon involved in a freak encounter with a rogue kaijuu. Though Kafka demonstrates his innate heroic nature and rescues Reno from certain doom, he is left gravely injured. While both men recover in a hospital, Kafka is seemingly attacked by another one of the beasts. As a result, he gains the ability to transform into a humanoid kaijuu with the strength and powers of the massive monsters menacing Japan. Dubbed "Kaijuu No. 8" by the military, Kafka resolves to use his newfound gifts for the greater good. Tied together by mutual respect, Kafka and Reno set out to join warriors like Mina at the forefront of the Defense Force.

Seven years ago, Chu Yunfei was struck by a dramatic change in his family and was stranded in the Pill King Valley in Zhongzhou. He returned to his homeland to take revenge and vowed to find out the truth.

Reeling from her recent breakup, Momo Ayase, a popular high schooler, shows kindness to her socially awkward schoolmate, Ken Takakura, by standing up to his bullies. Ken misunderstands her intentions, believing he has made a new friend who shares his obsession with aliens and UFOs. However, Momo's own eccentric occult beliefs lie in the supernatural realm; she thinks aliens do not exist. A rivalry quickly brews as each becomes determined to prove the other wrong. Despite their initial clash over their opposing beliefs, Momo and Ken form an unexpected but intimate friendship, a bond forged in a series of supernatural battles and bizarre encounters with urban legends and paranormal entities. As both develop unique superhuman abilities, they learn to supplement each other's weaknesses, leading them to wonder if their newfound partnership may be about more than just survival.