Tsukasa Atsumi is a salaryman who leads an ordinary, solitary life. On his way back from work one evening, he is saved from a demon attack by a mysterious woman in a ninja outfit. Introducing herself as Shizuri Ideura, she claims that demons target people like Tsukasa, who have Samurai Blood in their veins, and that her kind have been protecting them from the shadows. Told by Shizuri that the attacks are going to become more frequent, Tsukasa makes a deal to provide her with housing in exchange for his safety. To his surprise, he quickly finds out that Shizuri is a shut-in who loves to play video games whenever she is not busy with her ninja duties. As the two spend more time together, Tsukasa grows to appreciate Shizuri's company—and his feelings just might be mutual.

Sung Jin-Woo, dubbed the weakest hunter of all mankind, grows stronger by the day with the supernatural powers he has gained. However, keeping his skills hidden becomes more difficult as dungeon-related incidents pile up around him. When Jin-Woo and a few other low-ranked hunters are the only survivors of a dungeon that turns out to be a bigger challenge than initially expected, he draws attention once again, and hunter guilds take an increased interest in him. Meanwhile, a strange hunter who has been lost for ten years returns with a dire warning about an upcoming catastrophic event. As the calamity looms closer, Jin-Woo must continue leveling up to make sure nothing stops him from reaching his ultimate goal—saving the life of his mother.

A decade ago, 450-year-old vampire Ranmaru Mori was saved from the brink of death by Rihito Tatsuno, a young and innocent boy. Ever since then, Ranmaru has been working at the Tatsuno family's bathhouse with a secret: he wants a taste of Rihito's virgin blood as soon as he turns 18. However, his plan is threatened when Rihito falls in love with a girl on his first day of high school. Jealous and scared that Rihito's pureness will be ruined, Ranmaru begins to lurk in the shadows to protect him from any harm. During his operation, the vampire must keep his real identity hidden and make sure his target's virginity remains unsullied.

Though he grew up as an orphan, Nio Chirinu finds a place to belong: being a waiter at his adoptive grandmother's restaurant. But this peace does not last long; Nio and his sister Iroha are used as bait to arrest child abductors by Toshizou Hijikata and Souji Okita—two members of an infamous ronin group called Miburo. After the ordeal, Toshizou proposes that Nio join the ranks of Miburo and protect the people of Kyoto. Frustrated by his own weakness, Nio trains to match the swordsmanship of his new comrades. Even so, he struggles to be accepted by Tarou Tanaka and Hajime Saitou, the other Miburo members of his age. Determined to befriend them, Nio must discover his own sense of justice and become strong enough to prevail against all his enemies.