Over the course of the seires, Basara meets many people, from his allies and friends to rivals and enemies.
Jin is Basara's father. As a result of Basara's role in the tragedy that took place in the village, the two of them move to Tokyo. Jin gives up his duty to the world as a Hero and takes up photography in order to support Basara. In Volume II, while looking at a picture in the yakiniku restaurant that was photographed by Jin, Basara recalls how seeing Jin's photographs often used to help him deal with his trauma from the tragedy in the Village. The two of them share an incredibly strong bond. Even though Jin gave up being a Hero to the world, Basara still viewed him as the Hero that saved him. It's because of this that he originally decided to protect Mio and Maria.
Being an older brother to Mio, Basara has devoted to protecting her and even declares that he would save her how many times he needs to. Even after finding out that Mio and Maria have been deceiving him all along, he still rescued and protected her, living to his word. After Maria's spell backfired, Basara and Mio now share a Master/Slave relationship. The end of volume 3 serves as a turning point in their relationship. In a moment of passion following the incident with Zolgear, Basara loses his self control. He declares that Mio's virginity belongs to him and begins touching and kissing her. Before taking things too far, he eventually catches himself. As the series progresses, Basara's relationship with Mio grows through the multiple conflicts in the series and living their daily lives together. In light novel volume 10, Basara and Mio finally cross the line and have sex. Light novel volume 12 acts as a continued epilogue to volume 11. It's revealed that Mio was one of the first girls in the harem pregnant with Basara's child. Mio along with the other girls in the harem are currently engaged to Basara with their wedding quickly approaching in a matter of weeks. At the end of the volume, Basara surprises Mio with a wedding ring, and reaffirms to her his commitment to protecting her, the rest of his wives, and everything they hold dear.
Initially, Basara and Maria don't get off to the best start seeing as she lied to him. However Basara still promises to protect her since like Mio, he considered her to be his little sister and precious family. Maria would go on to act as a wingman of sorts for Basara and instigate lewd scenarios in order to help progress Basara's sexual relationship with the harem. He at first questions Maria's shenanigans and scolds her along with Mio and the other girls. However, as he gets more sexually experienced, he begins to think of Maria's actions as natural, and even in some instances directly asks her for input regarding various sexual situations involving the harem.
Basara's childhood friend who never gave up on him despite his exile from the Hero Tribe. After his intense duel against other Hero Tribe members (Kurumi Nonaka, Takashi Hayase) she was seen leaving with them and not going to school for a week which made Basara really depressed but that changed when he saw her in his house cooking (Beef Stew) and held her in his arms then declaring that she is the new house member in courtesy of Jin's help, indicating that she is one of Basara's very important peers.
Yuki's younger sister and also Basara's childhood friend before his exile from Village of Heroes due to an incident. Prior to his childhood, both Basara and Kurumi were in good terms as she used to call him as her big brother. After his exile, however, Kurumi began to despise Basara because of what he did to the Hero Tribe and her sister. After her battle with Basara, she reverted back to her old self calling him her big brother like she uses to but also at the same time began to develop feelings for him especially after moving in with him.
A former follower of Zolgear and responsible for kidnapping Mio until being betrayed by her master/creator/father due to her thoughts of having someone like Basara as a Master. She later joins Basara's group as the fifth female and third demon girl after serving Sheera. As the series progresses, her feelings of loyalty toward Basara grow romantic. She even takes on the "B" in his first name as part of her human world alias.
Chisato (real name Afureia). She is the "all too beautiful" school nurse of Hijirigasaka Academy and a former high-ranking god amongst the Ten Gods from the Divine Realm. Chisato is the younger cousin of Raphaeline, thus making her the cousin-once-removed of Basara. She is one of the main female protagonists of the series.
At first, she acted as a mentor for Basara Toujou for several issues in his life when he's protecting Mio and the others from various threats unbeknownst to him, but she later develops genuine romantic feelings for him and has on a secret relationship with him.
Similar to Yuki, Kurumi, and Takashi, Celis was a childhood friend of Basara who visited a lot when she visited the Japanese Hero Clan training and/or sparring with Basara. Similar to her three friends, she was shaken about the incident from six years ago, but she didn't blame Basara about the incident and like Yuki was saddened about his banishment from the clan even having hidden feelings for him. After meeting her friends again in Volume IX, she maintains her close relationship with Basara despite the incidents and being a member of the Vatican, even using her influence in order to keep the Elders from punishing them not hesitating to stand even in front of Shiba who tried to "attack" him.
When Basara first met Nanao she was timid and calm. However, as a result, Ornis interfering in the sports festival of their freshman year, they discovered each other's true identities. After Christmas, they became aware of each other as men and women. By the end of the third term of their freshman year, they began doing lewd acts together.
Basara and Shiba have a fairly complicated relationship. Basara is shown to be fairly fearful of Shiba considering his monstrous power and unpredictability. He believed Shiba to be a threat that only Jin could handle. In volume 9, they would come into direct conflict with each other as Shiba began enacting his plan for revenge against the Vatican and as well as the rest of the Hero Clan. While visiting the site of the tragedy caused by the Banishing shift, Basara is confronted and taunted by Shiba. This, in turn, causes Basara to think about how Shiba is able to see right through him. The idea of Shiba being able to see through Basara becomes pivotal as Shiba enacts his revenge plan and strings Basara along in order to manifest Kouryuu. Even after learning the truth about Shiba being a clone of Jin from Kaoru Nonaka, Basara only hardened his resolve, since Shiba became a direct obstacle to his and the girls' happiness.
Before beginning the battle to decide the fate of everything, Basara and Shiba have a conversation. This is where Basara comes to the conclusion that Shiba isn't necessarily wrong to hate the Vatican, but the two of them have a fundamental disagreement with regards to the Hero Clan and how to go about "saving the world. After his defeat for the first time and believing that he kill his girls, Basara´s feelings for Shiba grow on pure anger and want to kill him for this yet failed. after being saved by Hasegawa, making his ultimate wow with his girls, Basara was able to win against Shiba and seemingly kill him, but spare him and secretary make him his trump card in potential clashwith Ten Gods. Despite not forgiving Shiba for the attempt to kill his harem, Basara also sympathized with Shiba a bit, knowing and understanding what he had been through and led him a great degree of freedom, even let him live in Hasegawa apartment rent-free.
A member of the Hero Village and childhood friend of Basara. Takashi lost his mother when Basara's banishing shift went out of control, and ever since Basara was exiled their relationship hasn't been the same. 5 years later, Basara and Takashi are reunited, but Takashi still holds Basara responsible for the tragedy in the Village.
The Leaders of the Japanese Heroes who banished Basara due to him losing control of Banishing Shift after he and Yuki were attacked by Seito. He is shown to know their true intentions when it comes to Mio and their ideologies of "Protecting the Human World" going to whatever lengths to accomplish their goals. This soon grows into full distrust after being called back to the village due to their actions in the Demon Realm, after the way they questioned Mio's desire to live in peace with bias, use Yuki and Kurumi as hostages, and hearing their connection with Shiba and the Vatican.
Basara's classmate and also observer from the demon realm. After coming to blows over Mio, Basara and Lars decide to form a mutual alliance that would benefit both of them. Their alliance first bared its fruit at the conclusion of the Zolgear Arc, resulting in the death of Zolgear. Lars would play a pivotal role in Basara's assassination of Belphegor, thus freeing the demon realm from the tyranny of the cardinal sins, and setting the stage for peace negotiations between the current demon lord faction and moderate factions. Through all that their mutual alliance would grow into a genuine friendship.
One of Leohart's subordinate who attempted to kidnap Mio for his selfish desires, while imprisoned Maria's mother Shella as a threat to Maria in order to spy on Mio. For this reason, Basara see him as an enemy he had to fight against him in order to rescue both Mio and Maria from his grasp.
One of the veteran demons who serves both late Wilbert (Former) and Leohart (Current), Gald is one of Basara's rival prior to the Demon Lord Faction's invasion to Vereda City.
Demon Realm's youngest Demon Lord and one of Basara's formidable rivals. Due to Leohart's actions against Mio, Basara also sees him as an enemy until the young Demon Lord invited the Moderate Faction to settle their score via a seven-on-seven duel, where both warriors are. After the battle, Basara befriends with Leohart and them once as allies to fight against the corrupted ministers on the Demon Lord's Court.
Although he hadn't met her before, Basara does love his mother due to the amount of care that she has for him, which became more after hearing about Sapphire from Chisato.
At first, Basara sees Rikka as his responsible upperclassman. However, upon getting to know her, he takes notice of her cute and clumsy mannerisms and even finds them to be attractive. He's happy that she likes him, and the thought of having sex with her has crossed his mind multiple times. However fearing he might lose control and potentially hurt her, due to her being human and not having resistance to the spiritual, he's decided it's better for him not to try and respond to her feelings for him.
Although he hadn't met her before, Basara has the utmost appreciation for Raphaeline due to the lengths that she had gone for him just so that he could be born as he cried after hearing the truth from Chisato.
Like his father, Basara holds no grudge against gods but also no respect either. However, he shows don't afraid to clash with them if they're threatening those he cares as he challenges Ornis and almost killed him after takes Kurumi as a hostage and being possessed by Blynhildr. After events of Volume XII, after members of Ten gods witness his power, Basara starts preparing on war with them along with Shiba while his father was already in conflict with them.