Tsuboi Ryoutarou, known as Klein in Sword Art Online, ALfheim Online, and Project Alicization 1/4, is a supporting character in the Aincrad Arc who later appears through the SAO series. One of the SAO Survivors, and the Fūrinkazan (WWFM) clearing guild leader.

Bio

Japanese Name	壷井 遼太郎
Real Life Description	Has brown eyes and red-brown hair, a hooked nose, a slight beard on his cheeks and chin. Wears a wide red and yellow bandana keeping his hair up.
SAO Description	Has spiky hair. Wears a red ad yellow bandana, a red sakuran and white trousers, red and black light armor, brown open-toes boots, and uses a katana, looking like a samurai.
ALO Description	Has the same head look as in SAO (assumedly having donated to be able to customize it) and pointy ears. Wears a black and yellow bandana, a black bottom layer, a blue and yellow top with white trousers, a fiery red and yellow half-cloak, and uses black light armor and a sword, styled closer to Chinese myths.
Birthdate	1999-2000
Age	22 (↑Aincrad Arc), 24 (↓Aincrad Arc, Fairy Dance Arc), 25 (Phantom Bullet Arc)
Gender	Male
System Name	Klein
Race in ALO	Salamander
VR/AR	Sword Art Online, ALfheim Online, Ordinal Scale, Gun Gale Online, Project Alicization
Occupation	Chief Tactical Officer (最高作戦責任者 CTO) at Glowgen Defense Systems
Voice Actor	JP: Ishida Akira; EN: Greg Chun (adult), Amanda Miller (Child)
First Appearance	Novel: Volume 6 Chapter 12 (mentioned), Volume 15 Chapter 14 Prologue (actual); Anime: Alicization Episode 1; Game: Fatal Bullet DLC 3

Background

The day SAO released, Klein realized Kirito was a beta tester, and asked to help him learn the ropes. He and Kirito realized there was no logout menu item, then the SAO incident began. Klein refused Kirito's offer to go together saying he had to go back and help his friends out. He is always is on Kirito's side when it matters.

Personality

Ryoutarou is an open and friendly guy who brightens the mood by being around. Klein is always ready to help, and never holds a grudge. He stays with his friends despite the danger, and when Kirito faces up against the Death Gun, Klein is vexed and says that he should have transferred his character to GGO. Like Kirito, he wants everyone to stay alive, and gets angry when people do not value themselves as much.

Klein is often shown as a skirt-chaser, often dreaming aloud about girls and AI girls, including Asuna, Freyja, Skuld, and even Suguha before even meeting her.

Chronology

Aincrad Arc

Kōtarō and his friends buy a copy of SAO. Klein hangs out with Kirito for a day learning to use Sword Skills, and after Akihiko Kayaba's statement, Klein refuses to go with Kirito and finds his friends. They pass by each other occasionally later.

Red-nosed Reindeer

Klein's guild helps Kirito by fending off DDA guild members and later receives the looted revival item Klein should use on someone dying.

The Progressors

Klein and the others struggle but manage to defeat the Floor 56 field boss.

In August, 2024, Klein takes part in the raid on Laughing Coffin.

In October, Klein encounters Kirito, and Asuna in the Labyrinth of Floor 74. They meet and later rescue a party of "the Army".

In November, Klein is among those on Floor 75 who witness Kirito and Heathcliff's duel. Kirito takes the chance to apologize for leaving Klein behind two years ago, and Klein says Kirito owes him a real-world dinner for that.

Fairy Dance Arc

Ryoutarou attends the Aincrad Capture Commemorative Party at Andrew Gilbert Mills's Dicey Cafe, and is there in ALO when the New Aincrad update is rolled out.

Extra Edition

Klein takes part in the Deep Sea Plunderers quest in ALO.

Phantom Bullet Arc

On December 13, 2025, Klein fights monsters in ALO. Later, as he watches Kirito fight in the BoB tournament, he recognizes the Death Gun as someone from the red guild of Laughing Coffin.

Calibur

Klein invites Kirito to party up an clear the Inverted Ice Pyramid. Klein decides to rescue the NPC, Freyja, despite it looking like a trap, and she aids the party later on but is actually Thor in disguise who awards Klein with his hammer Mjöllinr. Klein gives it to Lisbeth. He also asks for Skuld's contact.

Mother's Rosario

Klein and Kirito help out Asuna and the Sleeping Knights. Later, he is there to see Konno Yuuki off, and then is at the commemoration picnic as Ryoutarou.

Ordinal Scale

Ryoutarou fight monsters in the augmented reality when Eiji suddenly attacks them and makes Ryoutarou lose his memories of SAO to his own Augma. Ryoutarou ends up in a hospital with a broken arm.

Later, he saves the SAO survivors trapped by Shigemura Tetsuhiro

Avatar Properties

Sword Art Online

|Stat | Value | Time|
|||
|Level | 59 | December 19, 2023|
|Level | 88 | End of game|

Fights with a katana "Karakurenai".

Skills as of Material Edition 02 (2008), out of 1000:

|One-handed Curved Blade | Katana | Light Metal Equipment | Lightweight Shield Equipment | Battle Healing | First Aid | Searching | Straining | Extended Weight Limit | Fighting Spirit (Hate Skill) | Sewing|
|||
|957 | 822 | 933 | 861 | 562 | 759 | 710 | 594 | 685 | 712 | 366|

References

Tsuboi Ryoutarou - Fan Wiki