Koutarou Satomi (里見孝太郎 Satomi Kōtarō) is a boy who started to live by himself to attend high school. He fortunately discovered a very cheap, tiny room called a rokujyouma (six-mat) for 5,000 yen (about US$50) a month. After he moved into room 106 of the Corona House, some unexpected "roommates" began appearing one by one!

He is also known as Layous Fatra Veltlion (Reios Fatra Bertorion in other translations), the Blue Knight of the fabled Forthorthian story. This is due to him and Clan being sent back to Forthorthe 2,000 years ago during their second battle. Up until the end of Volume 13, he tried to hide what happen to avoid causing problem for Forthorthe. He becomes captain of the Satomi Knights, after officially becoming Theia's vassal.


Koutaro fullbody

Koutarou is a lean though muscular young man with short brown hair (which is darker in the anime) and brown eyes and has average looks.

He is usually seen wearing his Kisshouharukaze High School uniform unbuttoned with a blue shirt underneath. But during his time stuck in the past, he spent the majority wearing the Blue Knight armor, but also wore a blue and white surcoat outside of his armor.

He has an athletic body due to his part-time job, and playing baseball. After his experiences in past Forthorthe, he gains a sturdier body with multiple scars due to multiple battles.


Clan described Koutarou as someone who is incredibly brash when he's joking, but can behave like a true knight when he's serious, something that has been noted by many of his friends. During non-serious matters, Koutarou is usually friendly, mischievous and even a bit childish. He often has no problem making jokes and playing pranks on his friend. He enjoys teasing Theia and Clan by calling it an honor to be "praised" by them after annoying them. He also enjoys hunting beetles, a hobby that he's been doing since childhood.

However, when it comes to serious or emotional matters, Koutarou becomes very focused, determined and carries a no-nonsense attitude towards problems, much like that of a knight. This earned him the trust and respect of even people who were his enemies to begin with. His friend Kenji even admitted that most of the best girls that he would love to date prefer Koutarou over him. After getting to know the invaders and spending over half a year with them, Koutarou stopped trying to push them out and instead wanted them to success in their invasion. After fighting in old Forthorthian for a few months, Koutarou became more calmer and level-headed during battle, and much wiser over all.

In battle, Koutarou is very merciful towards his enemies, only knocking them out or preventing them fighting any further rather then killing them. Throughout the war on Forthorthe 2,000 years ago, Koutarou never killed a single enemy that tried to kill him. While some of his opponents tried to take advantage of his mercy, this also earned him the respect and trust of old Forthorthians, who saw him as model knight to follow. He admitted he doesn't like fighting while dancing with Alaia, something that the other girls noticed and in turn prefer that Koutarou didn't have to fight.

Koutarou is also very respectful and gentle to those older than him and children. He's seen as something of a big brother figure to Sanae, Yurika, Princess Charl and Kiriha (when he met her in the past after being sent back in time). He also knows how to best cheer up or motivate the people close to him, helping them push forward when they need help the most.

Despite Koutarou's growing friendship with the invaders, he rarely asks much of any of them. Kiriha explained that this is the result of his mother's death and how she died saving him. Due to this tragedy, Koutarou would keep himself from getting too close and relying on people who'll most likely leave him someday. After the girls pointed this out, Koutarou stopped trying to push people away and started to make an effort to let other people into his heart.


Koutarou once had a very happy family with both his father and mother. However, due to his carelessness, his mother died of a traffic accident, which affected on how he bonded with others. He and his father also grew apart after the incident and their family started breaking apart. But he is able to recover thanks to Kenji and playing baseball.

Koutarou is rather fit, due to having been in the Baseball Team of his middle school before entering high school[1], and despite not having joined a sports team upon entering high school, he still makes it a habit to exercise his body in his free time. Upon entering high school, he rents a six-tatami mat room in the Corona House under the ownership of Shizuka Kasagi for 5000 yen a month. The cheapness of the room was what attracted him to the Corona House as his part-time job can easily pay for the rent and his living expenses. Although his dad had prepared money for him before going overseas for work, he abstains from using these funds as he doesn’t wish to burden his father[2].

To his misfortune however, the room he had rented in the Corona House, room 106, is wanted by several factions for differing reasons.


Harumi Sakuraba

Harumi is the first girl Koutarou meets and it was during the day he was going to get the results of his entrance exam[3]. He apparently saved her Knitting club from disbanding. She has a massive crush on him. She is apparently the reincarnation of the Ancient queen of Fortorthe. In the beginning, Koutarou would treat Harumi like a princess and behave like a knight around her. After volume 5, Koutaro would start treating her like he would his other friends. This often involves him teasing her and laughing at reactions that he finds cute.

She later inherited the memories and power from Alaia due to their overlapping feelings towards Koutarou, which granted her wishes to be of some use to Koutarou.

Kiriha Kurano

In the beginning, Koutarou saw Kiriha as the most troublesome of the invaders due to her polite and mature personality, forcing him to keep his guard up to avoid giving her his room. However, after half a year together, Koutarou realized that Kiriha was too gentle and that she wasn't planning on using force like she said she would. She admitted that he was right and revealed her real reason for coming to the surface. After that, the two become better friends, even seeing each other as their best friend.

Apparently Kiriha met Koutarou in the past when he had time traveled, but doesn't recognize him until she finds her mother's charm in Koutaro's belongings. She becomes more aggressive when she finds out. She is deeply in love with Koutarou as he was her first and true lover. She apparently is engaged to Koutarou without him knowing.

Sanae Higashihongan

After meeting the first time they had a bad argument. Later they formed a truce. They become really great friends later on. Since she can't eat she sometimes possesses Koutarou's body to taste food. She is also in love with Koutarou and would cling onto him all the time afterwards. Their relationship is compare to that of a big brother and his little sister that admires him. Koutarou has no problem with allowing Sanae to possesses him so she can taste food, play games using his body and even lets her sleep inside him.

Her love for Koutarou was strong to the extent that even after the memory loss after her spirit form merged with her human body, she felt nostagic when looking on his back. Later, in the fight with the return of the female evil spirit again in volume 11, she sprouted regretful words without thinking when she knew from Koutarou's aura of his intention to die even to protect her. That became the trigger which the return of her memories during her ghost form with the people in room 106.

Due to the merging of the 2 different personalities, she had some symptoms akin to those of multiple personality disorder. From time to time, she would split back to 2 forms: ghost and human, with the ghost (cheerful version) trying hard to made the human (introvert version) form to get used to Koutarou.

Yurika Nijino

At first Koutarou thought of her as a cosplayer. Later when they fought evil magical girl Maki he realized it. They became really good friends later on. She is the last person to realize that she is in love with Koutarou. Koutarou usually takes the role as Yurika's guardian due to her bad habits. Despite how roughly Koutarou usually treats Yurika, the other invaders have noticed that she the closest to Koutarou and the only one among them that he usually ask to do anything with. Kiriha had explained that the reason for this is because Yurika is the only "normal" one among the invaders and the only one who won't have to eventually part with him (Sanae being a former ghost, Kirika being from the underground, Theia and Ruth being from another planet).

Shizuka Kasagi

She is the landlord that rented the apartment to Koutarou for 5000 yen, and has unmatched martial arts capability that allowed her subdue the invaders and forced them to create the Corona Treaty to prevent any more physical conflict in acquiring room 106[4].

Shizuka began growing feelings for Koutarou after sympathizing with Koutarou's loss of his mother seeing as she has lost her own parents in a fire years ago. In volume 14, Shizuka realized she had fallen in love with him because they're very similar to each other: their parents died protecting them when they were children (In Koutarou’s case, only Koutarou’s mother), they were normal teens before the invaders got in involved in their lives and they were given powers by others, which made them feel that they are powerless on their own. For the last one, Koutarou told Shizuka she can rely on others like him so she can protect what she wants to protect. Touched by Koutarou's kindness, Shizuka confesses her feelings to him and that she still loves him regardless of whether or not he is strong.

Like Kiriha, she also teases him from time to time about him still not making Shizuka his girlfriend.

Theiamillis Gre Forthorthe

The seventh princess of Fortorthe and the only daughter of the current Empress, she had appeared on Earth attempting to take ownership of room 106 from Koutarou along with making him swear loyalty towards her as it had been a trial given to her to prove her right to the throne[5]. Initially, all Theia had wanted was for her trial to be accomplished as soon as possible, as seen by attending the same class that Koutarou is studying in. Later on however, she began developing feelings for him and had subsequently granted him the title of 'Knight' and 'Theiamillis' Blue Knight' in secret after helping her from the first attack of the second princess, Clariosa Daora Fortorthe[6]. Koutarou himself has also become less resistant in the concept of him becoming her vassal and had willingly become her knight (officially) when her mother was in trouble[7].

Ruthkania Nye Pardomshiha

Because she the only one whom not an invader, Koutarou treated Ruth with more kindness and respect than the others from the very beginning. Ruth fell in love with him because of his kindness. Starting in Volume 9, Koutarou began training Ruth at her request, teaching her Flairhan Pardomshiha's swordsmenship. She is first to find out his secret and started respecting him even more than before (which was described as additional effect of the admiration towards blue knight and her heartfelt love for Koutarou). She is even willing to throw her life away if he orders her[8]. Ruth is the one who subjected to Koutarou that he should form his own band of knights due to his stature as the Blue Knight; and the first one to join the Satomi Knights. Due to how much Ruth resembles her ancestor Flair, Koutarou often feels nostalgic whenever he teaches Ruth.

Clariossa Daora Forthorthe

Clan is the second princess of Fortorthe, and Theiamillis' rival. She had first regarded Koutarou as an enemy to be eliminated, especially with his intrusion to her attempts to assassinate Theia. By the end of Volume 7 however, Clan no longer treated Koutarou as an enemy and had instead tried to get his loyalty instead.

It was revealed in volume 7.5 and 8.5 that the space quake caused by Clan’s space-time bullet had sent her and Koutarou back in time, to the Fortorthe 2000 years ago. It was then that Koutarou and Clan met the Legendary Silver Princess, Alaia and their coup d'etat army. It was after this experience, with Koutarou, that Clan came to understand Koutarou's Kindness, personality and importantly - fallen in love with him.

After they returned to their timeline, Clan would receive requests from Koutarou time to time. During those interaction, she tends to have thought or say things like "I will definitely kill you/punch you" when he teases her or "you are in debt to me" to Koutarou. But, it is also mentioned that she is just acting, embarrassed by his teasing.

Now, Clan are more interested to become a befitting princess that Koutarou to acknowledge rather than just acquiring the throne through underhanded means.

Maki Aika

Maki is a magical girl that is part of the Darkness Rainbow faction that opposes Yurika's Rainbow Heart faction. She had initially thought of Koutarou as a manipulative man with access to unique and powerful magic, which made her fear and hate him after their first and second fight. This changed after Koutarou saved Maki's life using Signaltin in Volume 8 and the two fought along side each other against the berserked demon. Afterwards, the two often talk and laugh together and she would goes dere~dere whenever they are together.

After she was told that she was in contract with some "demon" (which she knew instinctively that it was with Koutarou) which expose every single fibre towards each other that was akin to marriage, she doubt if the emotion that she felt for Koutarou was real or magical in essence. After she broke the contract during her the fight between the Darkness Rainbow and Koutarou's invaders, she realized that those feelings were truly her own as it did not disappear along with the contract.

After the fight with Darkness Rainbow, she became one of the girls that regularly enters room 106. He later had her became the treasurer and the second person to join his band of knight in order to help her feel needed by him.

Alaia Kua Forthorthe

The famed Silver Haired Princess of the Legend of the Blue Knight, and a person that Koutarou had unwittingly saved upon being thrown into 2000 years in the past Fortorthe. After thinking that he had accidentally taken the credit of the real Blue Knight and aware that he could not leave Alaia alone, he helped Alaia in place of the real Blue Knight. Due to Koutarou's actions in protecting her along with helping her regain the crown, she had fallen in love with him. Koutarou holds similar feelings as indicated by his reply to her question if he would have been willing to stay by her side, should she have been the first to have met him. Despite knowing that Koutarou would return to his own time, Alaia gave Koutarou the legendary sword Signaltin and had asked him to keep the sword with him once he returns to his own time[9]. Although Alaia told him that this was to prevent similar conflict for the Signaltin, she actually hoped that she could continue protect him even if she can't be beside him.

In volume 12, Alaia appear in front of Harumi and passed her some of the memories and ability over Signaltin.

Powers & Abilities

At the start of the series, Koutaro was already in top physical form and a decent fighter. After meeting the Goddess of Dawn statue, Koutaro gained the ability to see and touch ghosts. In volume 3, Theia began teaching Koutaro traditional Fortorthe swordsmenships as part of his knight training and for the play. His overall combat abilities improved greatly after being sent back to old Fortorthe and fighting in the civil war. He could hold his own against dangerous armed fighters one-on-one using only his experience and unarmed combat skills, and could later overpower them when he fought them with even one of his weapons.

Because of the various types people Koutaro has befriended, they each have given him a bit of the power they have. This is a result of the love and trust they each have for him. From each one, Koutaro has gain:

  • Sanae: the ability to use his spiritual power to strengthen his body and sense. He can also see people auras to better predicted their next move. After she returned to her body, Sanae empowered Saguratin with spiritual energy.
  • Kiriha: a blue gauntlet that convert spiritual energy into fire and electricity for long ranged attacks.
  • Yurika: magic barriers that help protect him from most attack.
  • Theia and Ruth: the sword, Saguratin and a blue coloured knight armour that increases his strength and speed when in combat mode, the ability to fly, create force fields and has a super computer to aids him. The suit also controls the Blue Knight spaceship, allowing him to pilot the ship and use it to fight in space.
  • Alaia: the legendary sword Signaltin, which has unrivaled levels of magical powers when handle by both Koutarou and Alaia/Harumi (who inherited Alaia's memories and power).
  • Clan: A gauntlet that lets him communicate with her and her ship and summon his swords and armor.

in volume 16, Koutarou gain additional equipment Legendary Weapon System series-01A "Garb of Lord". Garb of Lord(GOL) is attached to his shoulders and autonomous supporting by emulating theia's thinking pattern. GOL have weapon variable property laser canon and high convergence beam cannon. It also provide additional defensive force with active distortion field generator and also additional propellant tank. He use GOL alongside with his new dual-wielding sword technique.


  • Koutaro seem to be a fan of hero and rangers based shows. Because of his love for those kind of shows, he got angry at the Sun Rangers. Because they all wore the same colour the first time (which he call the most important part), and the second time when there were two red rangers.
  • Before Volume 7, there were several hints throughout the first 6 volumes that foreshadowed Koutaro being Blue Knight and Kiriha Kurano's first love. It just wasn't explained how or why until after Volume 7.
  • After returning from the past, he would feel nostalgic and laughed in some occassions over the idea of "synchronicity" proposed by Clan whenever he see a person who resembled someone he knew in past. i.e. Harumi to Alaia, Ruth to Flairhan, and Elexis to Dextro.



  1. Rokujouma no Shinryakusha Volume 1 Chapter 2
  2. Rokujouma no Shinryakusha Volume 1 Chapter 1
  3. Rokujouma no Shinryakusha Volume 1 Chapter 3
  4. Rokujouma no Shinryakusha Volume 1 Chapter 7
  5. Rokujouma no Shinryakusha Volume 1 Chapter 6
  6. Rokujouma no Shinryakusha Volume 4 Chapter 6
  7. Rokujouma no Shinryakusha Volume 13 Chapter 1
  8. Rokujouma no Shinryakusha Volume 9 Chapter 7
  9. Rokujouma no Shinryakusha Volume 8.5 Chapter 4