Tobiiro Shadow

From Emily's Random Shoujo Manga Page:
It all begins long ago in the past. In a place near an ancient wall. The wall looks more like a cliff, really. Anyway, two cute children grew up together. Sumire is a gentle girl, and Yasuhira is a bossy boy, but he loves Sumire. When Yasuhira proposed marriage to Sumire, it was more like the confirmation of a long-held assumption that they would eventually wed. But they did lot live happily ever after. We see a bloodied sword, and someone crying…

Flash forward to modern times. These days, a school has been built near the ancient wall. It is such a tall, imposing wall/cliff thing, that naturally the students have made up ghost stories about it. Some of the girls a...