Oooku no Sakura

From matchlocks and cellphones to kimono and TV games, the cultures are blended, a modern Era with an "Inner Palace" inside the Osaka castle!? The only son of the Toyotomi Shogun, Hidekage, on mission with the inspection bureau "Carrion Cafeteria – Vulture", infiltrated this harem where pretty girls are gathered. However, the girls he saw there, were fighting for show, watched from outside an aquarium-like glass case. Those are not regular beauties! This is the start of a never experienced before forbidden school life! Source: My Anime List