The castle has a second name, Kasumigajo, which means the castle of haze. Nihonmatsu Castle was rebuilt as a modern fortress by Niwa Mitsushige, the first lord of the domain, who arrived in 1643. None of the buildings survive. What remains is stonework, earth banks, and about two thousand five hundred cherry trees, mostly Somei-yoshino with wild cherry mixed in.

The prefecture's own description says the flowers cover the castle site like haze lying over it. That is not a figure of speech invented for a brochure. It is what the second name has meant since long before the trees were planted, and the trees have grown into it.

The flowering comes in the first half of April, running into the middle of the month. Two and a half thousand trees is not a number you can see all at once, and the site does not try to show it to you. The ground rises in terraces.

That is what does the work. Flowers on an upper terrace are seen through the branches of the one below, so the white stacks up through the depth of the hill rather than spreading across it. Walk in close and it resolves into single trees again. Step back twenty metres and it goes soft. The name came first, but the trees have taken it over.