Before I get started, here's a link to an interview with Naoki Urasawa and Takashi Nagasaki from the Daily Yomiuri (English edition of the Yomiuri Shinbun) talking about Billy Bat.
And now, if you were kind enough to come back after reading the interview, here's a little historical background for chapter 7.

I already wrote some about the Shimoyama incident last month when it came up in the interview I'm translating, and I'm glad I did because in Billy Bat chapter 7 yesterday it happened.
In between what is known about the actual incident - Shimoyama going to Mitsukoshi department store on the evening of July 6th and being found splattered all over the tracks of the JR Joban line the next morning - we cut to scenes of Kevin talking to the crusty old comic artist who made the comic Kevin's comic appears to be a copy of:
Yup, that's the same bat alright.
And Kevin then learns that comic was inspired by this:

Japanese comic fans know what this is. But if any of you don't, then pay attention because this is the one that started it all.
This is Tezuka Osamu's first hit comic, and it stunned, fascinated and inspired kids all over Japan, sparking a comic boom in the '40s and '50s. From that came the key cartoonists who became responsible for the "golden age of comics" in Japan during the '70s and '80s, including Fujio-Fujiko, the team that created Doraemon and whoes name Urasawa parodies with 20th Century Boys Ujiko-Ujio.
The beret that Urasawa has his fictional mangaka wear, including the old man in
Billy Bat, was Tezuka Osamu's trademark and there after oft copied style.
Shintakarajima came out in 1947, only two years before Billy Bat is set, when
Osamu was 19 years old. What was particularly special it, in addition to the sheer 192 page size of the comic was it's cinematic style. Osamu's style may not look like anything new or exciting to contemporary readers, especially Urasawa fans, but it was revolutionary at a time when most Japanese comics were simple drawings covering only a few pages, and had a fixed, flat viewpoints right in front of the characters.
Tezuka drew it based on a proposal from Shichima Sakai, a popular cartoonist at the time. Sakai forced Tezuka to omit dozens of pages from his draft and to change the faces of some characters, according to Tezuka, and Tezuka said he wasn't really satisfied with the original version.
When Kodansha published a complete collection of Tezuka's works, he refused to reprint the original version and redrew the entire thing just for the collection.
Respecting Tezuka's intentions, Tezuka Productions for as long time did not allow reprints of the original either, even after Tezuka's death.
The rights to reprint the original, however, have since been licenced by Tezuka Productions to Shogakukan.
Anyway, after the old man gives Kevin a hard time when he says he learned to draw from copying other people, he tells Kevin that the person he copied must also have copied someone, and that person someone before, and so on, all the way back to ancient stone walls and the first ever drawing.
"The picture drawn on that [first] stone wall, let's say it was this bat."
He then cuts the conversation off saying he's going to sleep and that Kevin should too, since he probably hasn't slept for a while (for a first meeting he knows a lot, doesn't he?)
Elsewhere radio reports are coming in about Shimoyama and we know something has happened.
When we cut back to Kevin it's hours later and he's asleep at the old man's house. Kevin wakes up to find the old man gone and a note addressed to him on top of some comic boards that he was working on when Kevin showed up. addressed.
The letter reads, "Take this manuscript and get out of there."
Meanwhile, the police are just finding Shimoyama's body as Kevin looks at the comic.
"Hmm? Did I just hit something?"
Back at the crime scene an American army personnel introduces himself to the police as "Smith" as the chapter ends.
And that's it for Billy Bat until march 19th when chapter 8 is due.
In the meantime, here's something for you Urasawa fanatics to chew over.
Something that Urasawa says in the Yomiuri interview linked at the top ties directly into something in Chapter 7 (that is mentioned in this post). If you can figure that out, and it isn't that hard really, you will open a huge window to where Urasawa appears to be going with the Billy symbology.
Since I have time before the next Billy Bat, I think I'll try and find the English 20th Century Boys and see if I can offer some background to that, too.