Started reading Sword Art Online, and since it's my first time reading novels in Japanese, the first paragraph is already making me ask questions on Stack :P


I get the basic idea of the sentence, but the grammar coupled with unusual punctuation trips me up. What's going on in the middle part between the two commas? I'm not sure how it works, given that there are no particles or anything attached to キロメートル and it doesn't seem like the topic-wa relates to the rest of the sentence in any way, only to the part within the commas.

Also, if somebody knows what もあった is supposed to be in this context, I'd be happy to know.

  • 2
    "I get the basic idea of the sentence". What would you say that is?
    – Ringil
    Dec 29, 2020 at 20:11
  • 2
    @Ringil A group of workers spent a month surveying the area, and they say the diameter of the base floor is about 10km, and that the entire city block can fit into it. What bothers me is that it makes sense to structure it this way in English, but I know that I'm pulling this out of my butt basically. Dec 29, 2020 at 20:57

1 Answer 1


Your translation (in the comment) seems fine. The comma after 十キロメートル is used to rephrase or explain the word before it. In English, this use of commas is known as "parenthetical comma", but in Japanese, we often use a single comma.

You can replace this use of comma with actual parentheses like so:

They say the diameter of the base floor was 10km (which was enough to contain the entire Setagaya Ward).

Similar examples (note that there are only one comma in the Japanese versions):

  • 私の友達、花子はスキーが上手だ。
    My friend, Hanako, is good at skiing.
  • 世界初の人工衛星、スプートニク1号は1957年に打ち上げられた。
    The first artificial satellite, Sputnik 1, was launched in 1957.

For this も, see this and this.

  • Awesome. Thank you so much. Dec 31, 2020 at 10:48

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