So, the translator used the part-version chapters, (which I assume is from
bookwalker?)
and made this "case 02 part 1" as chapter 3.
In other sources like
comicwalker,
niconico,
piccoma, and the
volume version, the case number is the chapter.
So I'm wondering, wouldn't it be better if the numbering were changed to 1.1, 1.2, 2.1, etc.?