There are a few more details that point to the 1870s that I didn’t think to squeeze into the first page, namely:
- The declaration of mass recruitment of samurai family girls for Tomioka Mill so they could learn skills to take back home (and the rumors of foreigners drinking the factory girls' blood) began in 1872 and lasted only 10 or so years. The blood-drinking rumors specifically lasted only a short while before recruitment really took off. This puts the core setting of the story in the early to mid 1870s. [1]
- The foreigners at the mill (French silk spinners like the woman we see in this comic / equipment experts) were only present at Tomioka until 1875. After that, teachers & management were all Japanese folks. [1]
- The time period is also important as starting in the late 1880s until past the end of the Meiji era, labor disputes and far more oppressive working hours (up to 20 hours a day) clouded over the lives of silk workers [2], while in the 1870s working conditions were very reasonable (8-hour work days and Sundays off) [1] which aligns better with Ikuko's activities in the comic (going out on weekends and evenings)
- Ikuko’s father was a samurai, which suggests he was at least an adult by the early 1860s, and doesn't look very old. Ikuko also she seems to have a clear awareness of the change in her family’s status, so it’s likely Ikuko was even born before the Meiji Restoration (1868), somewhere in the 1850s-60s, making her the right age for the large scale recruitment for silk mills in the early 1870s. [3]
[1] https://kousin242.sakura.ne.jp/nakamata/%E5%BB%BA%E7%AF%89%E3%81%AE%E9%83%A8/%E6%97%A5%E6%9C%AC/97-2/
[2] https://hermes-ir.lib.hit-u.ac.jp/hermes/ir/re/11807/annals0010201810.pdf
[3] https://www.jobu-kinunomichi.jp/en/special/koujyo.html
That's certainly a great deal of evidence, so now the talk of a "war with Russia" seems somewhat odd, especially since I can't personally find any time Japan and Russia fought that would've been around that time. Again, it may simply be a side effect of the author condensing parts of history, as otherwise it implies some sort of 30-year time jump.
None of this detracts from the quality of the work, I should also say. It's a nice piece, and I don't expect perfect historicity from a work that is obviously just trying to give the vibe of "being set in the Meiji Era". The general backdrop of the pain and stress caused on society, with the main girls as our POV characters, by rapid modernization, industrialization, and imperial expansion is more important to the overall story than whatever specific year this would be set in. Again, you could easily replace the mention of "war with Russia" with "war in Korea" or "Boshin War" and it wouldn't change much.