Klein, whose real name is Tsuboi Ryotaro, is one of Kirito's closest friends and the leader of the guild Fuurinkazan. He met Kirito on the very first day of SAO's launch and receiv... ... Read more
Title: Guild Leader / Loyal Friend · Series: Sword Art Online
Appearance
Klein is a young man with a distinctive appearance: messy brown hair pulled into a spiky style, a red headband, and a goatee. His in-game avatar wears traditional samurai-inspired armor with red accents, reflecting his love for Japanese culture. He has a rugged but friendly face with narrow eyes that make him look perpetually mischievous. In the real world, Tsuboi is an ordinary young man with a friendly demeanor.
Personality
Klein is the definition of a loyal friend — dependable, caring, and always ready to help. He has a boisterous, sometimes perverted personality that provides comic relief, but beneath the surface lies a brave and selfless warrior. He deeply respects Kirito's strength despite occasional jealousy. Klein takes his guildmaster responsibilities seriously, feeling responsible for every member of Fuurinkazan. He never married in SAO, earning gentle teasing from friends.
Abilities & Combat Style
Klein is a skilled samurai-style fighter specializing in curved blades (katana). His skills focus on medium-speed, high-precision attacks with excellent parrying ability. He leads Fuurinkazan's coordinated group tactics effectively. While not at Kirito's or Asuna's level as a solo fighter, Klein's strength lies in leadership and team coordination. He survived to the front lines of SAO, proving his combat prowess was well above average.
Trivia
Klein's real name Tsuboi Ryotaro is rarely used in the series. He named his guild Fuurinkazan after the famous Japanese military principle (Wind, Forest, Fire, Mountain). He never found a romantic partner in SAO despite actively seeking one. After SAO, he continued playing various VRMMOs and stayed in contact with the entire SAO survivor group. He is one of the few characters who calls Kirito by his real name.
Role in the Story
Klein is Kirito's first friend in SAO, meeting him on the very first day of the death game. While Kirito leaves to solo, Klein chooses to stay with his other new friends, forming the Fuurinkazan guild. He represents the ordinary player experience in SAO — struggling, losing comrades, but persevering through friendship and determination. Throughout the series, Klein provides emotional support to Kirito and serves as a reliable ally in major battles, including the final floor boss fight on the 75th floor. He continues playing alongside Kirito in ALO and other VR worlds after escaping SAO.
Relationships with Other Characters
Klein's relationship with Kirito is the most enduring friendship in the series, starting from their meeting on day one of SAO. He deeply respects Asuna as a capable fighter and appreciates her role in keeping Kirito grounded. With his Fuurinkazan guild members, he acts as a protective leader who values every member's life. He maintains friendly rivalries with other guild leaders and is universally respected among the front-line players. After SAO, he becomes a regular part of Kirito's extended social circle, participating in cross-game adventures and real-world meetups.
