This entire volume is a flashback. We get to find out what happened right after Kubota picked up his "stray cat" at the end of volume 1 and learn how they became the odd but close couple we saw in volume 2 and thereafter. The story is told mostly in first person, from the viewpoint of young Iizuka Shouta, Kubota's next door neighbor. I don't recall seeing this viewpoint used much at all in the manga I've read thus far - it's rather interesting.
Shouta is a solitary child who doesn't get along with his classmates, doesn't play sports, and doesn't belong to any clubs. Both parents work, and his afternoons are usually spent alone in the family apartment, playing videogames and writing and drawing manga- and anime-influenced adventure stories . When his neighbor Kubota shows up one afternoon with another young man slung over his shoulder, unconscious, Shouta's life gets a lot more interesting. For one thing, the comatose guy has a hand that looks like an animal's paw, furred and clawed. For another, Kubota needs Shouta's help when the new arrival wakes up: he doesn't trust Kubota, but he's much less on the defensive with a child.
Minekura is good at portraying kids, and when Shouta's going off into his fantasies about what's really going on with his next-door neighbor, the story has a rather Neil Gaiman-esque feel to it. And although Shouta certainly learns a lot from this strange interlude in his life, Kubota and Tokito get a few lessons as well.
( Read more ... with spoilers! )
Question for the manga experts: I've been tagging my manga reviews with categories such as shoujo or seinen. But where on that spectrum does Wild Adapter fit in?
Oyceter's write-up on this (with spoilers)