Kuutei Senki ~Tasogare ni Shizumu Kusabi by Eushully (Jap)

In the world there is only an endless sky and islands floating in it.
The era of the Sky Pirates has arrived. About four of them is this story.
Gowan Manilla was once a man, and now woke up from a long sleep in the body of a vampire, forgetting about his past.
There is an invisible thread connecting it with three people:
- Patti Gran, the princess of the largest island nation who decided to become a Sky Pirate
- Thomas Benvesta, the youngest son in a large family, who decided to prove that he can be independent and brave
- Scientist Mashist Buckler, living for the sole purpose of creating the world's best warship
They all went to heaven, deciding to become Sky Pirates.
Heroes, using only old-fashioned maps, keep their way from island to island, fighting for their lives.
They are the freest people in heaven, and in front of them awaits the fulfillment of a cherished dream ...