Help me remember this anime/hentai.

The protagonist (most likely a pervert) goes to a town to search for "Oda Nobunagas"(I think) sister which he found a poster of her in a magazine only to find out that shes a loli. The protagonist does not "do" lolis. The rest of the scene is just sword fighting and war I think. I wanted to continue watching this but can't recall the anime.