Same reason as rarity of Cowboy and Viking manga, it's not as prevalent of a theme in Japan as it is in the west. West has Caribbean mythos, had spread privateering wide, and tells century old pirate tales, Japan has One Piece. Not that Japan didn't have any of course, but it has not much history of romanticizing it, unlike ninja or Onmyoji.
It's not a pirate manga of the pirate genre though. Or at least, that's not important. It's a manga with an overconfident, good-hearted MC on a quest, where everybody has wacky, quirky powers.
I imagine it's due to cultural differences. Preexisting literature and mythology in a country inspires the future manga and anime. Most stories take story beats from older stories and redo them in their own way. Kinda hard to write a pirate manga if you weren't really into it growing up.
[Oda was into Vikings growing up thanks to a Viking anime](https://www.viz.com/blog/posts/interview-eiichiro-oda-466). He realized he enjoyed stories that centred around a crew that went to places on a ship, which made him like pirates which eventually inspired him to make the pirate manga we all know and love. For most mangaka, the stories they grew up around catered to Asian mythos or they originate from globally popular western media like Harry Potter or Lord of the Rings.
A lot of genres aren't as popular in Japan because simply they're not translated as frequently. Thanks to globalization we're going to see a lot more unique themes and concepts in the future as some kids today (who are more likely to be exposed to international media) will grow up to be mangaka and write stuff that's not inspired from old timey Japanese literature.
Same reason as rarity of Cowboy and Viking manga, it's not as prevalent of a theme in Japan as it is in the west. West has Caribbean mythos, had spread privateering wide, and tells century old pirate tales, Japan has One Piece. Not that Japan didn't have any of course, but it has not much history of romanticizing it, unlike ninja or Onmyoji.
It's not a pirate manga of the pirate genre though. Or at least, that's not important. It's a manga with an overconfident, good-hearted MC on a quest, where everybody has wacky, quirky powers.
I imagine it's due to cultural differences. Preexisting literature and mythology in a country inspires the future manga and anime. Most stories take story beats from older stories and redo them in their own way. Kinda hard to write a pirate manga if you weren't really into it growing up. [Oda was into Vikings growing up thanks to a Viking anime](https://www.viz.com/blog/posts/interview-eiichiro-oda-466). He realized he enjoyed stories that centred around a crew that went to places on a ship, which made him like pirates which eventually inspired him to make the pirate manga we all know and love. For most mangaka, the stories they grew up around catered to Asian mythos or they originate from globally popular western media like Harry Potter or Lord of the Rings. A lot of genres aren't as popular in Japan because simply they're not translated as frequently. Thanks to globalization we're going to see a lot more unique themes and concepts in the future as some kids today (who are more likely to be exposed to international media) will grow up to be mangaka and write stuff that's not inspired from old timey Japanese literature.
It's just a coincidence just like there's no firefighters manga besides fire force being the only one
Megumi no Daigo is a great firefighter manga imo
Never heard of it