The second season of Yofukashi no Uta. Ko overcomes his confusion about becoming a vampire and decides to "like" Nazuna, while Nazuna resolves to make Ko "fall in love" with her. Without understanding what "love" even is, the two of them spend their nights together in a frenzy. Meanwhile, Detective Uguisu Anko is closing in with her plot to kill vampires, not just Nazuna. A vampire's weakness is "anything they were attached to when they were human" and so they all try to get rid of this weakness before it's too late. But, Nazuna has no memory of her human life. What is Nazuna's hidden past? Why did Anko start killing vampires? And what is the "secret" that Nazuna and Anko share? For Ko, Nazuna, Anko, a fun "late night" doesn't end here... a new "night" begins!

Two years ago, the death of Naoto Watari's parents left him as the sole caretaker for his younger sister Suzushiro "Suzu" Watari and forced him to move in with their aunt. So devoted is he to Suzu that he refuses to join clubs or even hang out with anyone, earning him snide comments and the title of "siscon" at his new school. But as long as Suzu is safe and happy, Naoto doesn't care what everyone else says. However, his sneering classmates may turn out to be the least of his worries. The sudden transfer of a girl named Satsuki Tachibana brings back traumatic memories from his past—a past she had a hand in making so unpleasant. Nasty secrets, unknown to Naoto, begin to surface with her arrival, threatening his new life.

It's the Taisho era—a time filled with the scent of romance, and people's hearts are still filled with compassion. Unzen, Sukayu, Unohana, Oshamanbe, and Aso are all ordinary (?) male students at Mayunan High School, who spend their days lazing around in the clubroom of the "do-nothing club" Earth Defense Club, and live together in the Kurodama dormitory. One day, while the five are taking a morning bath at the Kurodama dormitory, they notice something slimy moving in the bathtub. When they finally manage to catch it, it turns out to be a talking Pallas's cat named Nuru! Nuru has come from the distant future with a serious mission to inform them that the Earth is facing an impending threat of destruction. While he says he wants to protect the Earth, he says he's only come to warn them of the crisis, and that it's up to the five of them to decide whether or not they want to fight for the Earth... Isn't this just an attempt to dodge responsibility? The Defense Club members are suspicious. "If either is fine with you, I'll do it! That's more fashionable!" Unzen enthusiastically says. The five decide to fight with free will, and Nuru transforms them into the Fashionable Romantic Troupe using cat science. Meanwhile, a mysterious trio called the Bankara New Elite Squad are scheming in the shadows. They are plotting to take over the Earth.

Following the chaotic and heartwarming daily lives of Kaijuu who have come to Earth to conquer the world and live with their human masters.