Yoru herself states that she loves America because "...America made me powerful, terrifying and attractive".
America is the main contributor to Yoru being so powerful. America etched the fear of war into humankind.
Not only that, in this universe, they invented the nuclear bomb twice.
1. I want to make sure to stress that I've discussed all this, myself, unprompted.
2. America didn't etch the fear of war into humankind by itself, however substantially it contributed to it. The fear of war has to be as ancient as humankind. Yoru became substantially powerful on account of the rising fear of war well before America got re-involved in the narrative, just off of what was happening in Japan on account of the Chainsawman cult and the Fire Devil-- talk less of the global consequences of the first showing of the Falling Devil.
3. The symbolic mechanics implicit in your analysis (for lack of more concise terming) aren't consistent. It's not
America fawning over the War Devil, it's the War Devil fawning over America because America made war scary for people... but all this is supposed to mean "America is bad because it likes war", and not "America attracts war"... even though the narrative is presenting the narrative that
War likes America because of things America did. Yoru can sing "America the Beautiful" at the Super Bowl while Castle Bravo II gets dropped on Harare-- that's secondary to the core of the proposed interpretation that
War is fawning over America but we're supposed to understand this as symbolic of
America liking war.
4. Despite #3, if we're supposed to understand that there's supposed to be the message of "America likes war and is bad because of it" because Americans were cheering at nuclear bombs being dropped on the USSR (presumably still an enemy of the States in this timeline), what are we supposed to make of Japanese citizens being depicted as being gung-ho about killing a kid (Nayuta) randomly accused of being a witch by some stranger (Barem)? What do we make of them wanting to kill Denji when he transformed into Chainsawman to cut up a bunch of devils
in front of them, despite two women vouching for his killing devils at other times, one of them-- a Public Safety worker-- specifically saying he's not an enemy? What do we make of Denji (arguably a Japanese citizen) wanting to be Chainsawman partly because he enjoys the violence he partakes in while being Chainsawman? What are we supposed to make of the fact that Japan was participating in a competitive multi-nation operation to hoard as much of the Gun Devil as possible for the sake of war, or that the American president very solemnly used its portion of the Gun Devil in a bid to stop Makima-- who was an agent of the Japanese government?
5. The implicitly proposed symbolic mechanics dispense with everything about Yoru's character except for the fact that she embodies the fear of war. We're supposed to understand the message as "America is bad because it likes war" even though this is
War liking America, but what are the symbolic implications of War overtly liking Denji? Probably anything that tries to coerce the aforementioned "everything" into the proposed political commentary then dispenses with nearly anything about other characters (if the propositions even acknowledge they exist); I've discussed one of many such examples with another commenter above.
All this proposes that this manga has in the truest sense become anti-American and anti-war propaganda, dispensing not only with the depth of its narrative but also the depths of its characters...
but isn't even doing that in a coherent way.
Now, me, I'm a bit different.
Personally, I think Fujimoto wanted to do a bizarre kind of funny, but also be a little provocative.
