TV-Series
Description
Klein, originally named Ryoutarou Tsuboi, is a recurring figure in the Sword Art Online series. He debuted in Aincrad on November 6, 2022, quickly identifying Kirito as a beta tester and seeking his guidance in combat basics. Following Kayaba Akihiko's death game announcement, Klein chose reuniting with his friends over joining Kirito, a decision that separated them. This moment later cemented their friendship, fueled by Kirito's lingering guilt.
During SAO's death game, Klein founded and spearheaded the clearer guild Fuurinkazan. He played roles in significant events: aiding Kirito against the Divine Dragon Alliance on Christmas Eve to earn a rare revival item, inadvertently sparking a duel between Kirito and Asuna by revealing their level disparity during the 56th Floor GeoCrawler battle in March 2024, joining the assault on Laughing Coffin in August 2024, and fighting the Skull Reaper on the 75th Floor in November 2024. After that battle, he forgave Kirito for their initial parting, demanding a real-world meal.
After SAO's clearance, Klein transitioned to ALfheim Online as a Salamander, maintaining a similar avatar with dyed red hair. He attended the Aincrad Conquest Celebration in May 2025 and undertook the Deep Sea Plunderers quest. Watching the Bullet of Bullets tournament in December 2025, he recognized Death Gun as a former Laughing Coffin member. In the Caliber questline, he assisted Kirito's party in freeing Freyja (later revealed as Thor), receiving Mjölnir as a reward; he gifted the incompatible weapon to Lisbeth. His persistent flirtatious streak emerged again when he requested goddess Skuld's address.
During Mother's Rosario, Klein helped Asuna stall a rival guild so the Sleeping Knights could challenge the New Aincrad 27th Floor boss. He joined a barbecue at Kirito and Asuna's Forest House that escalated into a boss raid on the 28th Floor. Months later, he gathered in ALfheim Online with thousands to honor Yuuki and attended a real-world picnic with friends.
Learning of Kirito's critical state and the Underworld's peril during the Alicization Arc's War of Underworld, Klein immediately converted his ALfheim Online account to enter the conflict. This act sacrificed his long-established avatar and accumulated items, showcasing his steadfast loyalty and prioritization of friendship.
Klein embodies loyalty, protectiveness, and a lighthearted nature. He consistently fosters a positive group atmosphere, holds no grudges, and voices frustration when friends undertake dangerous missions alone. His recurring flirtatious behavior surfaces with characters like Asuna, Freyja, and Kazuto's sister. His deep value for friendship drives his actions, from the immediate sacrifice for the Underworld campaign to unwavering support across virtual worlds.
During SAO's death game, Klein founded and spearheaded the clearer guild Fuurinkazan. He played roles in significant events: aiding Kirito against the Divine Dragon Alliance on Christmas Eve to earn a rare revival item, inadvertently sparking a duel between Kirito and Asuna by revealing their level disparity during the 56th Floor GeoCrawler battle in March 2024, joining the assault on Laughing Coffin in August 2024, and fighting the Skull Reaper on the 75th Floor in November 2024. After that battle, he forgave Kirito for their initial parting, demanding a real-world meal.
After SAO's clearance, Klein transitioned to ALfheim Online as a Salamander, maintaining a similar avatar with dyed red hair. He attended the Aincrad Conquest Celebration in May 2025 and undertook the Deep Sea Plunderers quest. Watching the Bullet of Bullets tournament in December 2025, he recognized Death Gun as a former Laughing Coffin member. In the Caliber questline, he assisted Kirito's party in freeing Freyja (later revealed as Thor), receiving Mjölnir as a reward; he gifted the incompatible weapon to Lisbeth. His persistent flirtatious streak emerged again when he requested goddess Skuld's address.
During Mother's Rosario, Klein helped Asuna stall a rival guild so the Sleeping Knights could challenge the New Aincrad 27th Floor boss. He joined a barbecue at Kirito and Asuna's Forest House that escalated into a boss raid on the 28th Floor. Months later, he gathered in ALfheim Online with thousands to honor Yuuki and attended a real-world picnic with friends.
Learning of Kirito's critical state and the Underworld's peril during the Alicization Arc's War of Underworld, Klein immediately converted his ALfheim Online account to enter the conflict. This act sacrificed his long-established avatar and accumulated items, showcasing his steadfast loyalty and prioritization of friendship.
Klein embodies loyalty, protectiveness, and a lighthearted nature. He consistently fosters a positive group atmosphere, holds no grudges, and voices frustration when friends undertake dangerous missions alone. His recurring flirtatious behavior surfaces with characters like Asuna, Freyja, and Kazuto's sister. His deep value for friendship drives his actions, from the immediate sacrifice for the Underworld campaign to unwavering support across virtual worlds.