Asari's gotten a lot darker since SPACE FAMILY CARLVINSON; WAHHAMAN started out pretty much a goofball comedy, then suddenly turned SO horrifically bleak in the last couple of volumes--so bleak it made Manabe's OUTLANDERS read like LUCKY STAR--that I had to put it aside for a while before I could finish reading it. And he's doing it again here, with a "hero" recklessly wielding his "radiation power" with fatal consequences (that he blames on the relatively non-violent "villain"). Note on image 10 the image of the girl's skeleton being flashburned onto the wall behind her as Radioactive Man jacks up his "X-Ray Goggles" to "maximum power;" the cat, being smaller, simply succumbs quicker but they're both already deader'n hell and Radioactive Man killed them.
The villain ("Solarmask") is trying to coerce the Japanese government into going green and converting to solar power, while Radioactive Man--frequently to the horror of his scarred sidekick, Little Boy--wants a world in which everything is nuclear, and everyone happily drinks contaminated coolant-water for its "vitality-giving nuclear enrichment." ...Well, except the dead dogs and birds. Note also that when he changes into Radioactive Man, his hair is a wig. This is gonna be a short series, I'd wager.
Not too hard to figure out what recent events inspired this manga; Yoshitoh's countering the insane "Nuclear Boy" don't-worry propaganda you can still find (subtitled!) on YouTube.