Jin Domon

Aired after Episode 253 - In an alternate reality world that takes place in 19th century Japan, Luffy acts as a member of the secret police. This is made up of two adventures. In the first, Buggy makes trouble in the town. In the second, a mysterious girl named Vivi appears. This special contains several cameos from characters throughout the entire series. As of episode 424 there are now seven episodes in this special.(onepiece.wikia)

In the year 2031, a young man awakes from cryosleep to find the Earth overrun with giant, insect-like beasts known as Blue.

Hanaoka high school is an all girls' school, and the girls were pretty excited when they heard that boys were admitted into their high school. Smart and elegant boys, that's in their fantasy. However, in reality, the boys who were actually admitted are from the countryside and not smart at all, leave alone being elegant. And in fact, two of them are dirty perverts...