Leo Regulus

Leo Regulus (獅子座（レオ）のレグルス, Reo no Regurusu) is the Leo Gold Saint in Lost Canvas.

History
Prior to becoming the Leo saint, Regulus lived his early childhood with his father in the wilderness. After his father fell during a battle against Rhadamanthys, Regulus guarded the Leo cloth for many years and against numerous people wanting to take it from him until Sisyphus arrived to take him to become the new Leo Gold Saint.

Protect the Ship of Hope
Tasked by Sisyphus with protecting the ship and the present saints, Regulus makes his way to Tibet Himalaya and appears when Yato and the other Bronze Saints locate the Ship of Hope encased in ice. Knowing that the Bronze Saints didn't have the means to free the ship, Regulus took it upon himself to use his power to break the ship free from the ice it was trapped in. Only afterwards is it revealed that he and Yato had been training partners when they were younger and Regulus had already been hailed as a prodigy thanks to his advanced skills and cosmos.

While Regulus is acknowledged as being a genius when it comes to combat, he is soon discovered to be practically a novice in terms of culture as he is confused by the work and tools the Bronze Saints were using to repair the ship and was scolded by Wolf Junkers for handling one of the items incorrectly. He was further confused when it is revealed that the wood of the ship was responding to the care that was being given to it, similar to that of their saint cloths. At hearing this, Regulus was surprised to learn their cloths did such things and leads the others to realize that he's a prodigy only in terms of battle.

When Behemoth Violate descended upon the saints and the Ship of Hope, Regulus was the only one able to stop her before she could attempt another attack on the ship or the saints. Although he was mocked by Violate for his young age and still maturing power, Regulus accepted her challenge to see which of them was stronger and proudly declared that he would defeat her. Just as he began to get the advantage, Junkers called out how their test of strengths was causing more damage to the ship. Hearing this, Regulus decided he and Violate needed to distance themselves from the ship in order to prevent further damage and was able to launch Violate to another location farther from the ship. While he was proud for having overcome her strength, Regulus is surprised to see that Violate had managed to damage the hand pieces of his cloth in the process.

Ready to continue their fight, Regulus quickly discovers that Violate is a woman. Although wondering why a woman is on the battlefield, he decides he cannot bother himself with this knowledge and continues to focus on defeating her. Violate had attempted to land another attack on the Leo saint only for him to easily dodge and land on her arm effortlessly. Regulus admits that she is a powerful opponent but is taunted by Violate for only dodging her attacks. Regulus corrects her and says that he already had a good look at the way she fights and therefore is already considered the stronger opponent.

Thinking that Regulus was simply bragging, Violate attempted to attack him again but was shocked when he was able to stop her attack with a single finger. He then is able to launch her back and make her realize that he truly is a dangerous fighter. At this time, Regulus notices the dark ship of Hades and comes to see that Violate was a distraction to get him away from the ship.

Determined to make it back to the ship and other saints, Regulus tries to end the battle but finds himself paralyzed when Violate manages to hold him in place with her Seal Shadow. This allowed her to temporarily take advantage of the battle and allow Aiacos and his army to draw closer to the Ship of Hope. However, Regulus quickly adapted to her technique and was able to break free by using Violate's own attack against her. He explains that it was thanks to his eyes that he was able to see that she called upon the dead from the Underworld in her attack and was therefore able to see her strengths, weaknesses, and even source of power.

The two engage in another attack but Regulus was able to defeat Violate while picking up that she possibly had other motives as to why she fought. After Sisyphus and Aiacos began their fight, Yuzuriha is shown to have located Regulus after he had been struck down in a surprise attack by Aiacos. Despite his weakened state, Regulus recognizes Sisyphus' cosmos and that he is fighting against one of the Underworld Judges.

Regulus is later seen having managed to join the saints on the Ship of Hope and heading toward Hades' castle in the Lost Canvas. At the gateway, the saints encounter Sphinx Pharaoh who refused to let them pass and was able to take out several saints by ripping their hearts out of their bodies. It wasn't until Sisyphus allowed his heart to be judged by Sphinx and defeated him in a quick battle that the gateway started to open. Unfortunately, Sphinx managed to keep it from opening completely and revealed that only an attack with power similar to the Big Bang could now open the gate. Shion reveals that the saints possess such an attack but feels that they cannot accomplish it since the technique requires the combined cosmos of three gold saints.

To the surprise of the saints, Sisyphus managed to regain himself long enough to assist Shion and Regulus in performing the Athena Exclamation. Together, the three saints were able to open the gate and make their way into the Lost Canvas. Once the ship had entered the Lost Canvas, nearly the entire saint army was turned to stone with only Regulus, Shion, Athena, and Tenma being spared; Tenma having been saved by Yato while Regulus and Shion's positions as Gold Saints saved them. During their encounter with Acheron Charon, they are left with no choice but to rely on the specter for help as the Ship of Hope began to sink. However, the group is soon tricked when Charon requests Athena's hair as payment to take them to the shoreline and immediately sent it to Hades for him to seal Athena's cosmos. The remaining saints find themselves repulsed that Charon would easily commit blasphemy toward the goddess for the sake of money. Despite his greedy nature, Charon remained true to his promise of taking them to the shore since Athena paid him with her hair and he kept a small portion for himself. With Charon's departure, the saints continue to move forward.

Demon Temple Mercury
Having arrived at the first Demon Temple, Regulus appears eager to face their first opponent. As the group enters, Regulus and Shion fall victim to the powers of Mephistopheles Yōma and are frozen in time while Yōma reveals that he is Tenma's father, the true history of their family, and the battle against Owl Partita.

Demon Temple Venus
In the second Demon Temple, Regulus and the others are surprised to see numerous people writing records of every human to have existed. There they meet Balron Lune and are trapped by his whip when Tenma gets too noisy. Fortunately, Shion was able to free them from Lune's whip before he could inflict any damage upon them. As Shion is able to act as a decoy, Regulus is able to press forward with Tenma and Athena.

Regulus vs Rhadamanthys
He was shown arriving to the Saturnus Temple, preparing to engage in battle. Regulus attacks the Wyvern along with Tenma, only to have their attacks negated by the Specter. After the defeat of Partita, Regulus encounters Wyvern in the Saturnus Temple and after studying his physique and technique, Leo locks himself in combat against the Specter, vowing to surpass his power. Furious for revenge, Regulus reveals then to the Wyvern, that he is the son of Leo Ilias, the man who broke off his horn. Regulus reminisces about the quiet life he shared in the past with his father Ilias and engages the Specter without restrain. As Wyvern has attained divinity, Regulus is in clear disadvantage, expecting to revert the situation, he performs the devastating Athena Exclamation unassisted, which he learned from his mentor Sisyphus. The Wyvern effortlessly negates the attack of the Leo, who then resorts to summon the power of the twelve constellations and combines them into a single attack, releasing it as a concentrated shockwave known as the Zodiac Clamation. Regulus is consumed by the explosion, which the Wyvern survives unscathed. Having become an incorporeal entity, Regulus attacks the Specter once again, with the potent Lightning Bolt. Having inflicted his final attack on the Specter, and fulfilled his destiny as a Saint, Regulus rejoins his father in the afterlife.

Special Skills
A tactical genius, he is able to adapt to any situation in combat quickly, observing the capabilities of the opponent.
 * A major strength of this is the ability to learn the skills of the opponent which is capable of decoding techniques. This allows Regulus to manipulate the opponent's techniques against their will and perform them as well.
 * Possessing a great power and strength even among the Gold Saints, being able to perform techniques that could defeat a judge from Hades's army of specters in a single attack, and resist enough to survive the attack of Aiacos Garuda, and still support in the making of another Athena Exclamation, which he survived the explosion.
 * The ability to become one with the World or Nature, a strange state where Regulus is able to return despite being faded out of existence by the Zodiac Clamation. In this state he loses all traces of presence, in the words of Rhadamanthys "he was like the wind", his power was greatly increased allowing him to penetrate the defense of Rhadamanthys, something that even powerful techniques such as Athena Exclamation or Zodiac Clamation couldn't perform. It is unclear whether it was speed or something about this new state, but even someone on Rhadamanthys enhanced divine level could not be able to dodge his attacks nor fight back.

Techniques

 * Lightning Plasma (ライトニングプラズマ, Raitoningu Purazuma): Regulus focuses and releases his Cosmo in a series of small electric light beams, that attack the opponent at the speed of light. Unlike Lightning Bolt, it's impossible to see through several thousand punches launched instantaneously, as the enemy sees himself trapped in a destructive net of beams.


 * Lightning Bolt (ライトニングボルト, Raitoningu Boruto): The Leo Saint throws his fist at extreme speeds, creating a rift in the air through which he forces a high electric current generated by his Cosmo. That continues to attack the opponent even if it's destructive force is held.


 * Athena Exclamation (アテナエクスクラメーション, Atena Ekusukuramēshon): Although Athena Exclamation traditionally requires the combined Cosmos of three Gold Saints, in Lost Canvas, Regulus was able to cast it by himself after using it together with Aries Shion and Sagittarius Sisyphus. Such is the talent of Regulus, who surpasses all that his eyes observe. Since doing so did not break the Saints' code of one on one battles, he retained his honor when fighting against Wyvern Rhadamanthys.


 * Zodiac Clamation (ゾディアッククラメーション, Zodiakku Kuramēshon): In Lost Canvas, Regulus exceeded even the power of Athena Exclamation when he revealed this cataclysmic ultimate move. It calls upon the constellations of the zodiac to launch the attacks of all twelve Gold Saints at the same time. He had watched their moves while training alongside them in the Sanctuary, and unleashed them on the divinely empowered Wyvern Rhadamanthys to teach him the true strength of humanity.


 * Lightning Crown (獅子の大鎌（ライトニングクラウン）, Raitoningu Kuraun)

Family

 * Leo Ilias: Regulus' father.


 * Sagittarius Sisyphus: Regulus' uncle. Regulus first met Sisyphus some years after his father had died. He originally believed that Sisyphus wanted to take the Leo cloth for himself but soon realized that Sisyphus wanted the opposite. Regulus was trained by Sisyphus to become a great saint and the teen saw how his uncle was a kind and just person who greatly cared for those around him.

Others

 * Unicorn Yato: A friend and former training partner, Regulus has known Yato for several years and appears to enjoy teasing the unicorn saint on occasion.