Seiji/Ryuuji Tennouji

Seiji and Ryuuji Tennouji are one of the 5 "subjects" who underwent a clinical trial to cure their neurological disorders. They were college students that attended Reinan's Senjukuha Program (SP).

Appearances
Seiji was a short pudgy young man with brown eyes and reddish light-brown hair in a bowl cut with medium length sideburns. The front of his hair is a little wavy. Thin full length eyebrows. After developing a consistent and intense training regiment in Year 2 his physique increased significantly. Eventually developing to the point where it was comparable to his brother's in Year 4. Though he still and has a small build.

Ryuuji is a tall and muscular young man with broad-shoulders, he has hazel eyes and chocolate brown hair. He is a tall, well-built, highly muscular young man with hazel eyes and chocolate brown hair. Light-skinned. He is so big most of his companions call/compare him to a gorilla. His physique does change noticeably throughout the SP, growing 2-3 inches taller and his muscle tone got thicker too, but that is mostly due to his body naturally maturing rather than any significant muscular gain.

It was revealed in Year 3 that Seiji and Ryuuji do look like blood-related siblings, especially after Seiji started to get in shape.

Background
Seiji and Ryuuji Tennouji are the only sons of Tsuzuri and Yuugo Tennouji. Seiji has Dissociative Identity Disorder and first shifted into/manifested Ryuuji inadvertently when he was either in elementary school or kindergarten.

Seiji and Ryuuji spent their formative years living happily with their parents and receiving training from their father. Two notable events being when Seiji won a Spelling-bee and Ryuuji manage to dead-lift a washing machine.

Yuugo’s homosexuality was discovered when he cheating on Imamiya and it lead to him leaving the family in shame. This event directly caused the down-spiral in the relationship between Seiji and Ryuuji, in addition; without Yuugo's guidance, Ryuuji wasn't able to curb his increasingly reckless and violent tendencies.

They did not find out the exact details until Ryuuji tracked down his father in his early teens.

Personalities
Seiji was initially a very shy and self-conscious young man when he first arrived at Reinan, mostly due to his dysfunctional relationship with Ryuuji. He slowly but surely gained more confidence as he socialized with his fellow students and went out to more traditional social gatherings. He became exceptionally more proactive after his time with Yuugo in Year 2 revealed how he directly contributed to the martial arts side of his life.

Ryuuji was condescending, egotistical, and perpetually chasing ladies during the beginning of his SP experience, but has since become much more focused, caring, and friendly. Primarily due to Akiko cutting his ego down to size in Year 1 and watching out for any re-lapses. Now he is bold, steadfast, calm and gives an intimidating aura from his huge build. Other times w/ friends and teammates he's humorous and mildly kind - just enough to nudge them in the right direction or objectively call out their flaws. He experienced a period of self-consciousness in Year 2 when he hit a temporary wall in his progress.

Abilities
While Seiji has received training in the Rettetsu Ryuu he stopped practicing when Yuugo left. Ryuuji is a representation of the Infinite Fortifying Armor technique created do to Seiji’s Dissociative Identity Disorder. After being cured he can turn into his brother upon the consumption of whisky. Ryuuji is essentially an uber-human whose maximum potential is increased every time Seiji struggles against something physically: Enhanced strength, durability, speed, recovery rate, and a slightly increased reaction time. He prefers to rely more on street fighting methods then his fathers style. Though he was trained in Martial Arts Rugby Hoshino Kantarou on behalf of his mother and later did complete his training with his father.

Seiji and Ryuuji share memories and can telepathically communicate with each other. This originally manifested as Seiji and Ryuuji only being able to go over each other's memories. Although Seiji could only do so while he was in place, and vice versa for Ryuji. It grew throughout the first half of Year 4 as a small bleed-through of instincts and impressions that mostly occurred during fights; first becoming noticeable, and extremely apparent, during a training scenario where Akiko was in danger and Seiji telepathically screamed at Ryuuji to save her. This connection then became full-blown telepathic communication during their second match against Professor Nana in Year 4, allowing them to better strategize during fights.

Trivia
Shinji Tennouji has Dissociative identity disorder I based his father on Seiko Miyazawa from Kōkō Tekken-den Tough and Yuugo Tennouji from Steins;Gate and like Motoko Gettou Change 123 the nature of the style he practices caused each personality to develop a new body and they grew up as brothers.

Seiji and Ryuuji are based off of Mamiya Seiji and Mutou Ryuuji from Karate Shoukoushi Kohinata Minoru.