Nation's Name: Koninkrijk der Nederlanden (Kingdom of the Netherlands)
Capital: Amsterdam
Language: Dutch
National Flower: Tulip
Height: Unknown (roughly equivalent to Denmark)
Birthday: Unknown
Age: Unknown
The Netherlands made his official debut in a 2010 FIFA World Cup commemorative illustration alongside Denmark, Japan, and Cameroon. He's got spiky light brown hair (though it's been depicted as blonde in the anime and drawn in a softer style by Himaruya in sketches) and green eyes, though some official art colors them amber or blue instead.
Historically, he's best known for being Japan's main connection to the outside world during Japan's isolation period—he warned Japan about America's arrival in 1852, which is why they've stayed close ever since. Japan basically only trusted him for information about what other European countries were up to. There's also a story about him beating up Finland and Sweden after they tried establishing a villa in America, which England and France found pretty amusing.
He and his sister Belgium have a rocky relationship. Their personalities clash—she's mature and serious, he's laid-back and cool. After they both lived under Spain's roof for a while, things got tense. When the Netherlands declared independence, Belgium actually had to fight him over it. He later tried reuniting with her as one country, but religious differences, trade disputes, and conflicting diplomacy made it impossible. They stayed separate.
As for his character, he's the type to play it cool and be genuinely dependable. He's a sharp strategist, obsessively organized, and surprisingly muscular. He loves rabbits and hates anything tied or restrictive. He can be competitive—famously fought Turkey over who deserved the title "Tulip Country" (the Netherlands probably won that one). He's got an impeccably maintained kitchen and garden, and he's known for being stingy, serious, a bit neurotic, and somewhat tsundere. The sketches of him smoking weed are apparently a nod to Amsterdam's drug culture, though he's also drawn smoking a pipe. His character profile includes the note: "Of course he goes Dutch."
His most recognizable feature is his white and blue striped scarf, which he's rarely without. He has a small scar on his forehead, but nobody really knows where it came from or what it represents. He speaks in a Hokuriku dialect and owns a pet rabbit that's actually friends with Japan's dog, Pochi-kun.
His official human name hasn't been settled, though Himaruya has floated "Abel," "Govert," "Mogens," and "Tim" as possibilities.
Content compiled by AnimeList.moe from publicly available sources.