Naotsugu is a main character from Log Horizon, a 25-year-old Human Guardian with the subclass of Border Patrol. He is one of the earliest characters to appear alongside the protagonist Shiroe. In the real world, he was a businessman named Naotsugu Hasegawa who had recently started his career after college. He played the MMORPG Elder Tale heavily during his university years but quit the game about two years before the story begins, focusing on his job. His departure from the game contributed to the disbandment of his former group, the Debauchery Tea Party, an elite raiding circle that was never a formal guild. He returned to Elder Tale for the Homesteading the Noosphere expansion, only to be caught in the Catastrophe that trapped all logged-in players inside the game world.

Naotsugu is known for his boisterous and carefree personality, often referring to himself as an open pervert. He frequently makes lighthearted and inappropriate comments about women and underwear, which leads to comedic confrontations, particularly with the ninja Akatsuki, who physically punishes him for his remarks. Despite this crude exterior, Naotsugu is deeply loyal, protective, and reliable. He has a patient and laid-back attitude, willing to go along with whatever happens. He becomes flustered and nervous when women flirt with him, showing a softer side beneath his bravado. His primary motivation is to enjoy life in the game world and protect those he cares about. He is one of the few players who openly states he would rather remain in Elder Tale than risk returning to the real world.

Naotsugu’s role in the story is that of the party’s frontline protector and tank. As a Guardian, he specializes in defense and crowd control, using heavy armor and a large shield. His signature ability is Anchor Howl, which forces all enemies in the area to target him, ensuring that his allies are safe from direct attacks. He employs a Fortress build, focusing on high damage absorption and the ability to protect teammates. His subclass, Border Patrol, enhances his mobility and situational awareness, giving him strategic advantages in combat. While his offensive capabilities are limited compared to damage-dealing classes, his defensive skills make him an indispensable asset in raids and battles.

Naotsugu’s background as a former member of the Debauchery Tea Party connects him to some of the most powerful players on the server, including Shiroe and Nyanta. He met Shiroe several times in the real world, and they are considered best friends. Their friendship is a cornerstone of the series, with Naotsugu supporting Shiroe’s strategies and providing moral support. He also develops a comedic yet respectful dynamic with Akatsuki, often teasing her but ultimately trusting her skills in combat. Additionally, he builds a close relationship with Marielle, the leader of the Crescent Moon Alliance, and the two eventually become a couple, spending much time together.

Over the course of the story, Naotsugu evolves from a simple tank into a key figure in the guild Log Horizon, participating in major events such as the Abyssal Shaft raid and the formation of the Round Table Alliance. He learns about diplomacy and negotiation during encounters with the Asian server players and grows in his understanding of leadership and strategy. His development is marked by an increasing sense of responsibility, though he never loses his humor and approachability. Naotsugu remains a stabilising presence for his comrades, blending comic relief with genuine strength and dependability.