Tetsuya, in all his appearances, wears a long black coat with silver pauldrons, black boots, and black clothing underneath. The top of his clothing underneath his uniform is split to reveal his chest, covered by crossing leather straps. His hair is long and silver, a sharp contrast to Takuya Kimura's black spikes, with his bangs parted to either side of his face. Beyond his clothing and hair, Tetsuya is known for his green cat-like eyes and the Masamune, his seven-foot long katana that he is rarely seen without. His battle stance with the sword is to hold it over his left shoulder with the blade curving downward. Tetsuya usually wields the Masamune two-handed, presumably to increase the force of his strikes as he is capable of using it with one hand.
Tetsuya's personality is one of cold ruthlessness. He was not particularly anti-social, as he has friends, as shown in Takuya, Hokōra, & Akira. All the same, his cold exterior and professional attitude turn people away. He is very intelligent, and is respectful to those he deems worthy - he considered Seireitou Kawahiru a great scientist, but looked down on Ryan Getsueikirite and described him as "a walking mass of complexes". Tetsuya is confident to the point of arrogance. Well-spoken and somewhat graceful, Tetsuya is universally calm, collected, and in control. He can be frustrated and caught off his guard, but this rarely happens. In battle, Tetsuya retains most of the above personality traits, but becomes murderous and vengeful as well. His intelligence has increased vastly following his time in Asadal, and he has absorbed the knowledge of the Ancients there. At one point, Takuya even says he is greater than the Ancients. He has become highly cruel and delights in mentally torturing others, and in one of his iconic lines, asks his opponent what he cherishes so he may simply take it from him.