Joe Higan is a Nukenin – a former ninja who escaped his clan and is hiding from his violent past in rural America with his family. One night, he is ambushed by a team of assassins from his former organization who exact a bloody retribution on Joe and his family for betraying their ancient code. Rising from his seeming "death," Joe will re-emerge as his former self – Ninja Kamui – to avenge his family and friends. Kamui is a 21st century ninja, a shadowy anachronism who pits his ancient skills against high-tech weaponry with brutal finesse. He must face off against trained assassins, combat cyborgs, and rival ninjas to bring down the very clan that made him.

"My senpai from work... is tiny and cute." Shinozaki is an office worker who is taken care of and coddled by his senior team member Shiori Katase: a gorgeous, profoundly kind, loving, and diminutive woman. Shinozaki certainly hopes that she's not doing it out of duty... but her joy of doing so increasingly exposes her feelings!

In spite of his best time-leaping efforts, Takemichi Hanagaki continuously fails to prevent the present-day death of Hinata Tachibana, his adolescent love. The adult Takemichi grapples with grief and the ramifications of the Tokyo Manji gang's criminal empire—an unintended product of his timeline meddling. Though the gang once operated under the idealistic Manjirou "Mikey" Sano, it has now been taken over by the malicious Tetta Kisaki and, as a result, has abandoned its original optimistic intent. Despite feeling hopeless, Takemichi travels to the past once again to investigate Black Dragon, a rival motorcycle gang whose actions ultimately lead to Hinata's demise. There, he meets the young Hakkai Shiba, a fellow gang member whose older brother, Taiju, tyrannically rules Black Dragon. When Taiju brutally beats Takemichi in a one-sided street brawl, Hakkai attempts to withdraw from Tokyo Manji in apology—an act that Takemichi must prevent to spare Hakkai a grim future. Through a shared tragedy, Takemichi bonds with Chifuyu Matsuno, establishing a close comradery both boys desperately need. With Chifuyu on his side, Takemichi works to unravel the fates of Black Dragon's members, fighting to create a happy future for his loved ones.

To the outside world, Hanabi Yasuraoka and Mugi Awaya are the perfect couple. But in reality, they just share the same secret pain: they are both in love with other people they cannot be with. Hanabi has loved her childhood friend and neighbor Narumi Kanai for as long as she can remember, so she is elated to discover that he is her new homeroom teacher. However, Narumi is soon noticed by the music teacher, Akane Minagawa, and a relationship begins to blossom between them, much to Hanabi's dismay. Mugi was tutored by Akane in middle school, and has been in love with her since then. Through a chance meeting in the hallway, he encounters Hanabi. As these two lonely souls spend more time together, they decide to use each other as a substitute for the one they truly love, sharing physical intimacy with one another in order to stave off their loneliness. [Written by MAL Rewrite]