Near the school (and about 5 mins walk away from my mums house) is a small green that has this kind of dip in the middle. The story goes that back in the Victorian times that used to be a pond, but there was a tragic accident, a horse drawn carriage overturned and plunged into the pond drowning a lady. Now, extrapolate this out and I guess yeah there’s loads of people during all the time to tragic back story altering carriage accidents back in the day - you gotta 100% give that one to fantasy isekai mangaka.