Reinhard is a tall, handsome young man with flaming red hair and blue eyes. He wears a variation of his Royal Guard uniform even when he's off duty.
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. However, his power is so great that upon awakening a small part of himself, Subaru already considers him another monster. Reinhard considers 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 villain the opportunity to surrender while hoping he will not have to take extreme measures, such as being forced to kill him. 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.
Reinhard was born the son of Heinkel Astrea and Louanna Astrea. At five years old, he obtained the title of Saint of the Sword while the Hakugei fought against his grandmother, Theresia van Astrea, who passed away due to the disappearance of her powers. His grandfather, Wilhelm van Astrea, blamed Reinhard and Heinkel for her death, so they did not get along. Eventually, he joined the Royal Guard, becoming an expert swordsman, and befriended Julius Juukulius and Ferris.
During one mission, Reinhard, along with some forces, arrived at the Argyle House to face a group of animated corpses. Miles, who was responsible for what was happening, tried to escape and ignored Reinhard's warnings, forcing him to kill him. 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, and 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.
Master Swordsman: Reinhard is highly skilled at using the sword.
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.
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 Regulus Corneas, and it is tough enough to withstand the latter's authority. A simulation of Reinhard also drew Reid against a simulation of Puck during Subaru's second trial in the Witch of Greed's tomb. 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.
- According to the author, any text written in Reinhard's POV is considered a major spoiler.
- According to the author, Reinhard is likely the 7th or 8th Sword Saint in his lineage.