Laughing Under the Clouds(2010)

In the eleventh year of the Meiji era carrying swords was forbidden by the government and those known as samurai were slowly fading away. However there were plenty that didn’t like those changes taking place in Japan and inevitably the crime rates increased. Japan’s only resolve was an inescapable lake prison. While the prison had no other way to access it but only through water, the 3 boys of the Kumo family were assigned to transport the criminals to their new "home". Although... is that the only thing they were doing...?

Included one-shot:

Volume 1: Utakata ni Warau (泡沫に笑う) - 2 chapters