Tenma Unomiya is a short young man with hetero-chromatic eyes, purple to his right and green to his left and long maroon hair with many hair antennas. Because of these characteristics, he is often mistaken as a girl. In the manga, Tenma has a much shorter hair that ends in shoulder length. His outfit consists of a long black uniform with a few red and yellow thin lines. His neck is covered by a glowing yellow light in the borders of his collar. He has a belt that has a heptagon in front, one on each side with the color red and four glowing yellow lines. His whole arms are covered by slightly loose sleeves, and hands covered by black gloves with a red circle and glowing yellow outline. At the age of 10, Tenma had both eyes of the same color, bobbed hair with straight bangs, and only two streaks of hair antennas. After the time-skip, Tenma now has significantly longer hair (similar to his anime appearance) that he keeps in a ponytail. He also wears an eyepatch outside of battles, but replaces it with a monocle in missions.
Tenma is a person who acts out of common sense, which is shown while he was prompted at Rokuro's hot spring pools and later appeared in his mental realm. He likes to give nicknames to people, and rarely calls anyone by their given names. He is also shown to be rather arrogant and antagonistic towards his allies, and shows a greater amount of hostility towards enemies. He also speaks in a very crude manner; rarely using honorifics and does not speak formally even towards fellow Guardians and higher-ups. As a child, Tenma does show kindness; all the while having a crudeness that he would carry growing up. While he did have some conflicts with Shimon during their childhood, his good disposition is often reiterated by others, such as Senri. Her death apparently affected Tenma greatly, and the rituals surrounding the succession of Kijin would further contribute to the deterioration of his mental well-being. After gaining the Kijin shikigami and foreseeing the future, he gained a nihilistic outlook in life. Despite his nihilism and mild antagonism towards his allies, he is later on shown to actually care about the well-being of the people he is involved with; and is willing to do some questionable things, such as purposefully breaking the rules in the Castle Games and cutting off Shimon's leg, to further contribute to the greater good of his allies (in this case, preventing Shimon's predicted death).
As shown, he did not panic during chaos.
His care for the greater good coupled by his nihilism is strong enough to make him sacrifice whatever he must, including himself and his own reputation. After losing his foresight ability, his actions are no longer governed by what he foresees would happen and had a clearer inner self due to the influence of the fallen Great Yin disappearing. Because of his own belief that he must be surrounded by gruesome death and must suffer the same fate, he temporarily loses sight of his own purpose after staying alive longer than his foresight told. He quickly gains his newfound purpose during his fight with Gabura, revealed to be Mitarashi dango; his favorite food. His experience with having clearer thoughts also causes him to lose much of the influence his prior nihilism had on him; deferring to more practical and reasonable actions, but retains his crudeness Still. Tenma is described as calm and cool-headed. As shown, he did not panic during chaos. He often smiles in front of his enemies to ridicule them. He has also shown confidence with his strength when he volunteered to help Kankuro Mitosaka instead as he believes it will be faster that way. He has a tendency of not listening to others when he is interested in something else but is considered pretty handy to have around. He is able to easily get in other people's nerves as shown when he asks Miku Zeze about her age which also struck a nerve with Subaru Mitejima. And it can also be noted that he likes calling others using nicknames he just came up rather than their names like calling Rokuro Enmado a Runt, Flatty to Benio Adashino, Money Grubber to Kengo Ujii and etc.
39;d argue a lot.
He also has a sweet tooth, as he has an extreme fondness for Mitarashi Dango. Tenma was born and raised on Tsuchimikado Island along with his siblings and cousins of the Unomiya house. He attended the Tsuchimikado elementary school with his siblings and Shimon with whom they'd argue a lot. Tenma, while attending the Tsuchimikado elementary school, was often subjected to scolding as he didn't find much interest in school resulting in him skipping and being late most of the time much to the ire of Shimon. It is implied that he was a loner during that time as once during a conversation with Shimon he claimed he didn't need friends. At a later point in time when Tenma was 10 years old the ritual for the new successor, Kijin, of the Unomiya house began as the mark of the centipede appeared on the hands of Tenma and 9 other members of the Unomiya family including Senri. It was then noted by Shimon that the Unomiya family was absent for many days after this.
Later he was ordered to bring the Twin Star Exorcists and Sae to Kyoto.
The ritual for title of Kijin, as explained by Shimons father, was akin to kuduko in which the Unomiya's, ten candidates, who were selected for the ritual would have to fight and kill each other for the title. Ultimately, Tenma succeeded the ritual and became the sixth head with the last person he being his older sister Senri, whom he loved very much and noted by Shimon to be the only person "he can't stand up against". However, it was during that last battle that Senri's true feelings were revealed and she showed bitterness and envy toward Tenma who she noted before to have tremendous innate potential. Senri with her last breath told Tenma that he will forever be alone and in pain with no one to understand him and that he will go to hell for his actions. It was shown then that Tenma's left eye color had changed from purple to green, caused by the power he gained from the ritual. He can be briefly seen when the Twelve Guardians assembles. Later he was ordered to bring the Twin Star Exorcists and Sae to Kyoto. Upon his arrival, He strikes using what looks like an Air Fissure Bullets and easily defeated Kinasa the basara who attacked the Twin Star Exorcists. He also closed the massive dragon spot in the area without using a talisman which shocked Rokuro and Benio. He then traveled with the Sae and Twin Star Exorcists to Kyoto and he soon left them stating that his job of escorting them is accomplished.
During his break time he buys all the Mitarashi Dango on a certain store.
He later participated in the Heavenly Blue Earth Ritual in hopes of permanently closing the dragon spots, being the one in the middle to channel the spell and having the Twin Star Exorcists to protect his area. But lamentable, Tenma and the others were trapped when Kuranashi turned the Spell Ritual against them and was only freed when Sae returned to the Ama No Mihashira. He is present when Mikage Tsuchimikado announced that he will be the acting Head Exorcists while Arima is missing and was later seen participating in finding Arima like the other Heavenly Commanders. During his break time he buys all the Mitarashi Dango on a certain store. During the Twelve Guardians Meeting, Tenma asks Miku Zeze how is she still looking so young while being already being 56 years old which left an impression against him and later when Mikage Tsuchimakado reports them about the oracle stating that Arima Tsuchimakado is already dead, Tenma then tells the other Guardians to find Kuranashi and he will be the one to take his head while wondering if Kuranashi will prove a little challenge considering that he is suppose to be the strongest Basara. After Mikage Tsuchimakado explained the details of the Rikujin Shinka Ritual to the other three Guardians present, Tenma suddenly arrives and quickly agrees with the plan, however things went against planned as Kuranashi then counters their spell by lifting the city and sending Giant Kegare to them.
As Kuranashi's Scheme continues, Tenma fights off giant kegares like the other Guardians. He was later seen still fighting with him using his Sword as a flying hover board but the Kegare this time combined to form a more powerful version. Though already tired from all the fighting, Tenma and the other Guardians then continues the Rikujin Shinka Ritual after the Kegares were defeated to safely return the Floating Narukami City back to its right place but unfortunately it is then revealed that it was all part of Kuranashi's Master plans. With the 12 Guardians weakened from fighting of Kegares and casting the ritual, Tenma and the others were successfully trapped by Kuranashi's own spell, with Tenma saying that he will not forget Kuranashi's name. Like the other Guardians who were absorbed, Tenma's weapon was used by Kuranashi during his fight with the enraged Tatara, with Kuranashi commenting that The Kijin Tenma Unomiya's weapon was effective as expected. In Episode 50, An illusion or possibly his spirit appeared with the others to Rokuro and Benio to cheer them up when they were trying to stop Abe No Seimei's plan. After Rokuro and Benio manage to stop Abe No Seimei, Tenma and the other Guardians were freed. Later he was at a rooftop eating Mitarashi Dango while discussing with Arima Tsuchimikado how everything turned up as he offers the latter to try his Mitarashi Dango. Tenma meet Rokuro for the first time while relaxing in a hot spring.
He asks Rokuro if he was one of the Twin Star Exorcists as his face was unfamiliar and comments on Rokuro's opinion that everyone got the same will he has. Soon, He was later seen on Taigetsurou with the other Twelve Guardians with their House Representatives that is going to give Rokuro the chance to join one of the families. As the meeting progress, He then comments that Miku Zeze's uncle owe Rokuro an apology for scorning him and the Adashino House but also that Rokuro needs to go the Magano in the island to see how delusional for him to say that he will settle scores with Ijika Yuto. Shimon asks why is he here and that Rokuro and Mayura don't need Tenma's Babysitting for he was assigned as their protector. As the battle progress, Tenma saved Rokuro from a giant impurity and he later took Rokuro back at the clinic and explained to him the details about Abe No Seimei, King Of Impurities and how Magano was created. He is frequently mentioned through the next chapters specifically when Narumi Ioroi shared his opinion of the Twelve Guardians' ranking in strength and when Ikaruga Shimon is suggesting the best possible houses for Rokuro to join. During Rokuro's battle with Kankuro Mitosaka, he is shown watching as Rokuro uses his Shikigami but is shown laughing as it turns out to be a sphere of Ohagi. He ceases laughing after Rokuro activates it and transforms into armor for his arms which emit great power that truly impresses him as Rokuro sends Kankuro flying.
When the first match ups have been decided, Tenma's opponent is Ikaruga Shimon and their match will be the 10th fight of the first round of the tournament. In the match he held his own but his opponent started to overpower him forcing him to use his enchanted gear and cut off Shimon's leg. After the games, he was made to apologize to the Ikaruga House and was put on house arrest. Tenma later visited the hospital, where the staff were shocked to see him before he approached Shimon's room and was casual at his and his brother's shocked faces. Tenma was grabbed by Keiji Ikaruga who condemned him for cutting off his brother's leg and threatened him but Shimon broke it up. However, Tenma's taunts led him to be punched by Keiji. After Shimon had Keiji leave, Shimon told Tenma that he knew he held back. Tenma was irritated by this deduction as well as Shimon telling him he doesn't want the secrets of the mission, since he didn't feel he won.