Ok, so if anyone is curious, I've narrowed down the time frame so that anyone who doesn't know the traditional dates of japan can figure out the time frame.
The Meiji era is a time period that started about one year after the Meiji restoration. The time frame of the Meiji era is 1868-1912. The manga says the "12th year" so I'm assuming that means 12 years after the start, that'd be 1880. It also says that he got transported 140 years into the future. though it does not give a specific time frame. 140 years after 1912 would be 2052, while not impossible I don't get "futuristic" vibes from this manga. though we've only seen the house (I've not looked at the raws.) which I assume to be a shrine and those are usually kept with the original aesthetic, so even if it was the future, I doubt it would change. Moving on, 140 years after 1880 would be 2020, more plausible but still....and lastly 140 years after 1868 would be 2008. This seems more likely to me personally but you decide. Hope you enjoyed my little history lesson XD
Does anyone know where I can buy a physical copy of this book in english? (I've found many places to buy the book but it's in japanese)
Unfortunately this manga hasn't been licensed in English, so there's no official English copy yet...
Damn, that sucks. Thanks for letting me know.