Reinhard is a slender, tall and extremely good looking young man with flaming red hair and sparkling blue eyes that radiate strength and determination. He's described as an epitome of a gallant knight. His beyond average looks and his open, calming and approachable personality makes him very popular with people, especially with the ladies.
As expected from a Royal Knight, he's usually seen wearing his Royal Guard uniform that is primarily white with some red finishes and golden accessories. When he's off duty, he is usually seen wearing his "casual clothing" which is also a uniform but not as detailed and complex as his Royal Guard one; the uniform is primarily white with some purple accents and an Astrea crest on his left shoulder. Since he's the current generation's Sword Saint, Reinhard always carries his Dragon Sword Reid around his waist.
Reinhard is a respected and kind gentleman with others. He is fair, clean, brave, and willing to fight next to justice even when he is not in his hour of work. He is known as a "knight among knights", and is widely trusted among the people of Lugnica. He only uses his sword when necessary, since, in addition to being a rule, he does not intend to hurt an ordinary person.
He mentioned that his specialty is fighting monsters, but his power is so great that upon unleashing just one of his attacks, Subaru already considered him another monster. Reinhard considered this as an offensive comment, implying that he does not like being judged as someone dangerous even when he has good intentions.
He is always looking for a way to solve things, even to the point of giving a Sin Archbishop the opportunity to surrender while hoping he will not have to take extreme measures, such as being forced to kill him. In his fight against Regulus, he even went as far as asking him to stop and leave the city, even after the Sin Archbishop had already killed him and decimated everything it their vicinity. He also respects the decision of his friends despite the fact that sometimes they criticize him for engaging in matters that do not correspond to him.
Due to his calm and kind demeanor, Reinhard is rarely angered. However, in both Ayamatsu and Tsugihagu he has visibly furious upon witnessing the mass deaths of innocent civilians. He was similarly angered upon seeing that the Witch Cult had resurrected his grandmother's corpse. This also leads to Reinhard's one arguable negative trait; he has shown to be slightly judgemental, continuing to insist that the resurrected Theresia "was not his grandmother" even after she was shown to have regained her emotions shortly before her death.
Reinhard was born the son of Heinkel Astrea and Louanna Astrea. He was loved by everyone. His grandmother's first thought upon seeing him was that he was "a child loved by the world". Two years after his birth, his mother fell into a Sleeping Beauty state, which shook the whole Astrea family to its core. At the age of five, he obtained the title of the Sword Saint after his grandmother Theresia van Astrea passed away during her fierce battle with the Hakugei. The reason for her death was the sudden loss of her Divine Protection of the Sword Saint which mysteriously disappeared midway through the battle, transferring to young Reinhard. His grandfather, Wilhelm van Astrea, blamed Reinhard for her death, causing their relationship to plummet, leaving only his father who still cared about him. Sadly, his relationship with his father gravely deteriorated as well. After he gained the aforementioned blessing, his father became an alcoholic, and gradually starting to blame him for Theresia's death as well; it didn't take long for Reinhard to be despised by his closest family members. As the strongest individual in the Royal Kingdom of Lugnica, he was forced to join the Royal Guard, becoming the strongest weapon in the Kingdom's possession. Somewhere down the line, he met and befriended Julius Juukulius and Ferris who are to this day two of his closest friends.
During a rescue mission involving Crusch Karsten and the House of Argyle, Marcos Gildark tasked Reinhard to keep an eye on Prince Fourier and the knights accompanying him. While Julius and the rest of the knights were disposing of the reanimated corpses, Miles, who was the culprit behind the incident, tried to make his escape, ignoring Reinhard's warnings, and refusing to surrender. After his attempt to get rid of Reinhard had failed, the latter was forced to incinerate him along with his Winged Dragon as he could not allow the valuable information to reach the Vollachian Emperor.
Six months prior to the events of the series, during the time when the entire Lugnician royal family died, one of the Nine God Generals, Balroy Temeglyph, planned a coup while Reinhard, Julius, and Ferris were in the country because the Emperor of Vollachia wanted to meet Reinhard. The three of them got involved with Balroy and Julius was accused of killing him. Fortunately, they were able to prove his innocence by defeating the real culprit, Gramdart Holstoy.
Divine Protection (加護 Kago): Reinhard has the ability to wish for any Divine Protection he wants, such as the Divine Protection of Judgement (審判の加護 Shinpan no Kago) during the battle at Priestella. These Divine Protections are granted to him by the Od Lagna, which is even capable of creating new ones that never existed before, but sometimes there are errors in conveying his intention, and Reinhard doesn't get a proper Divine Protection. This ability is confirmed to be unrelated to him being the Sword Saint.
- Sword Saint (剣聖 Kensei): Reinhard is the current Sword Saint as the current holder of the Divine Protection of the Sword Saint (剣聖の加護 Kensei no Kago), which he inherited when he was 5 years old. According to the author, even if he didn't have this Divine Protection, Reinhard would be pretty much the same.
- Various combat oriented Divine Protections: As mentioned above, Reinhard holds an insanely rich arsenal of Divine Protections. To name just a few of his combat oriented abilities; 80% of all magic attacks from all six magic types is dispersed away or neutralized, he gets stronger when he's standing under the blue sky, rainy sky, night sky and when he's bleeding, he can move at superhuman speeds, any projectile thrown against him automatically changes their trajectory making him unable to get hit by projectiles, he cannot get ambushed and the first attack will always miss unless he willingly takes the hit, the following attacks will also miss unless he's physically unable to avoid them, he is a master in unarmed combat and he will automatically master any weapon he picks up even if he never saw or handled it before, just to name a few. In total, Reinhard is said to possess more than one-hundred Divine Protections.
Master Swordsman: Reinhard was born with an insane sword talent. He was 5 years old when he first picked up a sword and immediately defeated his father Heinkel Astrea. At that age, Reinhard was already stronger than the average Royal Knight, only being able to be bested by exceptional and renowned knights the likes of Julius Juukulius and Marcos Gildark. Although not as skilled as the legendary Reid Astrea, Reinhard's sword skill is unparalleled.
- The Swordplay of the Astrea Family: Reinhard unleashes a devastating attack that destroys everything around him and splits space in half. When Reinhard decides to perform the attack, the mana surrounding him is sucked from the atmosphere and the temperature of the air is noted to drastically drop. His blade begins to give off a brilliant white light and upon slashing down on the opponent, the area in front of him is blown apart, as seen when he blew up the Loot House in the first arc, and the Church in the fifth arc. Coupled with his Divine Protection which allows him to always land his first attack, this attack is devastating for the opponent. Reinhard usually uses it as his opening attack on extremely strong foes like Regulus. And though strong individuals like Elsa have been able to survive this attack, it is generally capable of vaporizing human beings as shown in the Oboreru IF. A downside to this technique is that Reinhard requires a weapon in order to perform it, but said weapon, even if of astounding craftsmanship, will be destroyed immediately thereafter. The sole exception appears to be the Dragon Sword Reid, which is said to be indestructible.
- Dragon Sword Reid's Slash: Reinhard unsheathes his blade whenever the sword deems his opponent worthy of it's divine power. Reinhard will take an offensive stance, usually lifting the blade far above his head, preparing to end it with a single strike. Similarly to his Swordplay of the Astrea Family skill, the blade will slowly start to emit a dazzling white light which will soon enough engulf the entire battlefield, blinding the opponents. If he's aiming to cleanly dispose of the unlucky foe, he'll swing the blade, cutting everything along its arc. In his simulated battle against Puck however, Reinhard used the Dragon Sword in combination with his aforementioned sword skill; with a single swing, the Sword Saint unleashed a destructive wave that incinerated everything in its path including the Beast of the End. Along the blade's slash the sky split in half, leaving cracks running across the sky, the ground crumbled and the mana swirled in a vortex, completely destroying the world itself. In the next instant, the world will be born anew without fail. Both attacks are the very peak of what Reinhard van Astrea is capable of doing.
Defective Gate: According to the Artificial Spirit Echidna, Reinhard's gate is unable to release the mana inside of his body back out into the atmosphere, though she mentions that he is able to absorb an incredible amount and that it doesn't cause any harm to his body as he uses all of his mana to boost his physical abilities. Because of this, he can make others unable to use any magic or spirit magic while he's absorbing mana. Also, Reinhard has no affinity with magic, making him unable to use it at all.
Pseudo Spirit Affinity: Minute Spirits are attracted to Reinhard and try to heal him whenever he becomes injured. However, he is unable to order or use the Spirits himself. This attraction is on par with Julius' Divine Protection of Gathering Spirits (誘精の加護).
Equipment: As the Sword Saint, Reinhard wields the Dragon Sword Reid (龍剣レイド Ryuuken Reido). The sword can only be drawn against opponents it deems worthy for it to be used against. Currently, Reinhard has only been confirmed to have drawn his sword against Cecilus Segmunt and Theresia van Astrea, although according to Wilhelm van Astrea, there was a third occasion where it was drawn. He can also use the sword in its sheath as shown during his battle with the Sin Archbishop of Greed, and it is tough enough to withstand the latter's authority. It is mentioned that the sword was created by the Sword God (剣の神 Ken no Kami).
- According to the author, Reinhard's birthday is January 1.
- The author named Reinhard after Kaiser Reinhard from Legend of the Galactic Heroes.
- According to the author, any text written in Reinhard's POV is considered a major spoiler.
- The author stated that Reinhard van Astrea is the strongest character in the series and no stronger characters are scheduled to appear in the story.
- Despite him being the strongest, he still wouldn't be able to kill/defeat Satella, due to their powers. Reinhard wouldn't be able to bypass her immortality and Satella would not be able to land a finishing hit.
- Reinhard is likely the 7th or 8th Sword Saint in his lineage.
- By the time he was 8 years old, the Kingdom already issued the "Reinhard law", preventing him from visiting other countries freely, meaning he was already considered a national threat by that age and the strongest character in the series.
- He could destroy the world fairly easily.
- Even if he lost all of his Divine Protections, Reinhard would be about as skilled with a sword as he is now, only being unable to defeat those who are basically cheating.
- The author has stated that Reinhard would be able to defeat Od Lagna in a battle.
- Reinhard would be able to fight Volcanica one-one-one if he can draw the Dragon Sword.
- He is the most handsome male character in the series, according to the author.
- Reinhard's favourite colour is unsurprisingly red. He likes the sparkliness and its visibility.
- As shown in Oboreru, Reinhard with most of his Divine Protections disabled is still strong enough to defeat Cecilus Segmunt and kill both Puck and Halibel while being gravely wounded from his fight with the aforementioned Blue Lightning.
- According to Reinhard himself, Regulus was the second person who forced him to use the Dragon Sword Reid (sheathed or unsheathed).
- The author stated he'd be able to move through a rainstorm without getting a single drop of water on him.
- He's so powerful that even Subaru is unable to defeat him, despite having unlimited tries and unlimlited ways of tackling the "Reinhard threat". In fact, no matter which character would decide to try and destroy the world, they wouldn't be able to, as Reinhard would always stand in their way and stop them.