Yuzu Soft manga
“Aqua Eden” – a man-made floating island where gambling, sex trade, and thievery is allowed by the government. But there is one more thing that lurks in the streets of the island–Vampires. Mutsura Yuuto is working with one of them, and together with a few other members of their group, they fight to uphold morals on the island taken from jcafe24
A new teacher finds himself a newly appointed position as a teacher at an all girls school... on an island... in the sky! How will he make do in his new surroundings? Or the residents of this island who seem like they came from another world? And what's more, how will he fare at being a teacher?