Tengoku (天国 Tengoku?), nicknamed as Goku (悟空?) is an U.A. High student attending in Class 1-B, who having gone without an nickname was given the name as Gashadokuro (がしゃどくろ/ 餓者髑髏 lit. "starving skeleton"?) by the population during the Vangaurd Action Squad attack Forest Training Camp lead by the Wild, Wild Pussycats due to his quirk, Spectral Body.
Tengoku was the second child born in the Yamanashi Prefecture between Tokuyama Yuki and Shigaraki Sarutobi. However during his initial birth, his quirk manifested when 1/3rd of an ribecage appeared, ultimately killing Tokuyama in the process. The ribecage wrapped around him which protected him and stopped anyone from teaching him due to an fiery cloak that made it impossible to go though. After approximately five hours, the ribecage demanifested allowing doctors to perform an full physical examination, and to place the now deceased Tokuyama into a bodybag for burial.
Since due his quirk manifesting at an early age, and it began to manifest in unpredictable intervals through his early childhood, he was constantly in quirk counselling to get it under control. However his older brother Hayate would blame him for their mother's death, which resulted in Hayate in attempting to kill his younger brother. His father Shigaraki would save him, which made Hayate believe his father betrayed him, which ultimately awakened his own quirk. Not only did it allow him use the quirk that's similar to Spectral Body, it also allowed manipulation of fundemental forces. Hayate using his newfound quirk would try not only kill Tengoku but even Shigaraki. However Shigaraki used his own quirk, Primordial Fire to defend himself, and during the fighting interaction which caused attention as the fight broke out in an neighbourhood, Hayate fled and was never soon again.
Since then Shigaraki helped with Tengoku's quirk to control it, which eventually lead to being allowed to control it at will. Before entering the U.A. Entrance Exam, he accomplished his goal and was able to fully manifest theb ribecage at will, which offered great defense.
Tengoku is an young man standing 1.90m in height possessing dirty blonde hair and light green eyes. Thanks to constant physical exercise and fitness training, he has an muscular physique with which shows, but not enough that it's equal to a body builder.
Tengoku is an very caring and even polite individual who seeks to save others from harms and threats of villains and even quirkless "criminals". Due to the years following his mother's death brought by his quirk, he has held an hudge grudge against himself, hating himself for his mother's death and his older brother becoming an villain. He vowed to his father to save his brother from villainous intent, even if he's forced to kill him, he hopes to save him and hopefully earn some degree of forgiveness. Before joining U.A., he's noted to had the personality of an fully matured adult, being cautious and thinking before actin in most situations, otherwise is very reserved about his emotions and feelings. However after joining U.A., he began to open to the wider world, now having made friends in Class 1-B, he's shown to actually be very worrisome and concern for the welfare of others.
As to not let suffer the same threat, Tengoku would often act on his own as an lone wolf and therefore usually wasn't good at social interaction, often reserving to himself even having opened up to everywhere. He rarely speaks unless he must, which is often in life or death situation. He opens himself during the trainig camp where the Vanguard Action Squad attacked, which he expresses concern, but also held an intelligent leadership voice, commanding and coordinating with 1-B. Kenod noted he projected his voice in an coherent manner that made it understandable to follow. He's incredible tactical, observing and analyzing the Vanguard's combat power, and would relay the information to any nearby students, or teachers. He's someone who would self-sacrifice to save others, shown with the unexpected Apotheosis transformtion of Gregory van Helsing, using his quirk beyond what he can to combat against the superpowered Gregory, which almost cost him his life due to fatigue exhausation and Apotheosis destructive power.
Tengok is one of U.A. top students in the first years, mainly due to his training in various martial art and his quirk of Spectral Body. Highly intelligent and capable combatant, despite his age he's considered to be ready for an "side kick". Due to prior limitations that it had no offensive capabilities, he was train in unarmed combat, trained in different styles of taijutsu; Budō, Judo, Aikido and Kenpō. He's more commonly utilized Aikido as its was created to not only defend themselves, but leave the attacker unharmed, an perfect martial art for an hero. He also had created his martial art styles, often going towards speed and agility other then strength and brute force. However he has developed his style in consideration to his quirk, to is referred as Spectral Martial Art (霊の体術 Reitaijutsu?), an taijutsu specifically for Spectral Body.
Tengoku's quirk is called Spectral Body (幽霊の体 Supekutoru Bodi?). By far one of the most unique and most most citizens and even U.A. students and professional heroes, terrifying quirk that allows him to manifested an skeletal humanoid being around him to act as an "ultimate defence" (究極防御 (kyūkyoku bōgyo?). During his own birth where his quirk manifested in the worst possible time - 1/3rd of an human ribecage manifested while result in the untimely death of his mother due to this. However periodically his quirk would just manifest without form of control til he was capable of controlling throughout his junior years. By the time he went for the U.A. Entrance Exam, he was fully capable of controlling his quirk and can manifest an completed ribecage. When the ribecage manifests, an fiery cloak forms aorund him and the ribecage, granting him seemlingly impervious defense to most manner of assaults. It's been noted that he himself is unable to attack others, but with the defensive capabilities, he's capable of using an enemy's own strength to cause harm, shown during the entrance exam where the robots constantly break itself when impacting it. He can still move though his speed does get hindered due to Spectral Body.
However Tengoku soon was capable of manifesting two skeleton arms and shoulders, thus allowing him to further strengthen his quirk to obtain offensive capabilities. He considered this the "second stage" in his quirk development during at the U.S.J. Incident where his quirk was able to hold out the nomu before it broke through its defenses and greatly harming him. After the incident he soon continously manifested the quirk and soon enough gained an head and strengthen skeleton body. During the U.A. Sports Festival, his quirk took on an drastic change during the obstacle course, capable of now using this quirk as an monsterous attacking force, easily tearing throught the robots. However it seems he can manually choose what to manifest as during the one on one matches, he only manifested the ribecage and a single arm to use, mostly likely the size of his quirk be too great for the arena.
However during the Vanguard Action Squad's attack of the training camp, fellow classmate Gregory van Helsing was under emotional intense due the villains, causing him to activate Apotheosis and undergo an transformation of an fox-like being. Under this condition, he was classified truly insane and went on an rampage, having killed two villains of the Vanguard. Under this predicament and the fact students where in danger when he appeared to Mandalay and Deku. Going beyond his very limit, he activated his Stage III Spectral Body form which became known as the Armoured Titan (装甲巨人 Sōkō Kyojin?). As the Amroured Giant, he gained access to greater capabilities of manipulating the flame that manifests with his quirk to tangile weapons capable of greater offensive power, defenses increased amost 10x greater then his Stage-II. He's capable of manifesting and shield and focus manipulation of the fires to battle against Tengoku's Apotheosis form which became an highlight with the teachers at U.A. due to the signifance of the fight. It was said he used this form for over 10 hours after the Vanguard left as Apotheosis was still activated, and used his flames to eventually calm Gregory down after pinning him with his shield. He has yet to remanifest this form since the Training Camp Incident.