A very cross Saki arrives just in time to witness her ex go toe-to-toe with the vicious steel beam-wielding ghost of an idol. Saki had seen Kurou’s cuts heal immediately and even saw his detached finger regenerate, but had never seen him die, which is what happens when Nanase whacks his head off.
I was surprised Saki didn’t let out a scream upon witnessing such a horrifying sight, but in possibly an even more unsettling sight, Kurou’s head is whole again and he’s alive and well just a minute or so later.
Having taken her best shot, Nanase can’t really do anything else other than try to kill Kurou again. Kurou is also able to predict her generally mindless movements, but even when he snaps her neck she’s back as quickly as he was. Perhaps sensing a stalemate, Nanase disapparates to fight another night.
We learn through Kotoko that Kurou is the result of his insane grandmother performing human experimentation on members of the Sakuragawa clan and the flesh of the immortal mermaid and future-seeing kudan. Kurou was the first to consume both and not immediately keel over and die, but in gaining the abilities of the monsters he ate, he naturally became less human.
This is no doubt a large part of why Kotoko is so enamored of Kurou—they both inhabit the space between humans and the supernatural, and who else would be able to deal with either of them? But while Kotoko is determined to make Kurou her husband, Kurou seems to be less enthusiastic and even fatalistic about the prospect of such an often annoying brat being his only hope at happiness.
Kurou’s reunion with Saki is pleasantly cordial, underscoring how there’s still love there for both of them and things ended so abruptly as to lack closure, and thus cause emotional confusion upon seeing one another again. The reason Kurou is there is because some of the monsters in the city sought out his aid without using Kotoko as a go-between, demonstrating effectiveness of her efforts to make him less frightening to her supernatural pals.
Meeting in Saki’s apartment, where Kotoko must endure Kurou staring at his ex (who says she lost weight due to her police job, not depression), Kotoko explains how a “monster of the imagination” like Steel Lady Nanase comes into physical existence. It’s essentially a matter of humans playing a game of telephone with each other regarding a rumor, which is spread, embellished, and refined until it is given name and a form.
Typically monsters of imagination aren’t grave threats to humanity, but Steel Lady Nanase clearly is, and the rumor that eventually gave her form was essentially supercharged by the power of the internet to reach more people and gain viral status. Thus, the wiki Saki found wasn’t created in response to Nanase, Nanase was created because of the wiki.
Kurou can fight Nanase all night long, every night, but she’ll never be defeated for good until a new rumor, one simultaneously more enticing to people and less lethal to people than the current iteration. That won’t be easy, but Kotoko is already a powerful conduit for human-supernatural networking, which means no one’s better suited for the job.