Koyomi Araragi is a third year high school student who survived a vampire attack during spring break and barely regained his human life in the time that followed as a boy with remnants of vampiric traits. He can see in the dark, his eyes turn red when he gets angry, and he heals incredibly fast. As a result, he questions his lifespan. He remains scared of morning sunlight despite the fact that it no longer has any negative effects on him. Koyomi is a laid-back person whose only real friend at school is Tsubasa Hanekawa. He's a poor student, close to failing every class except math. It is revealed through conversations that he's quite knowledgeable with anime; a fact even noted by Nadeko Sengoku once. Although he is shown to be attracted to the other girls, he turns their advances down due to his loyalty to Hitagi. Other characters seems to speculate that Koyomi is a lolicon, particularly Mayoi and Hitagi, with Hitagi thinking that Nadeko is a "threat" to her. He is very noble, which is why Hitagi is attracted to him. He is willing to help others at the cost of his own life. As such, the female characters he has helped are quite attached to him. He feels most comfortable talking to Mayoi, Shinobu and, from the Second Season on, to Yotsugi about his problems. Koyomi is the only person who thinks that his family relationship is bad, with Karen and Tsukihi thinking otherwise. His parents were revealed to be police officers. His personality is portrayed more clearly in the novels, where his inner thoughts show him to be much more perverted and intelligent than the anime leads one to believe. Due to events prior to Kizumonogatari and Bakemonogatari, Koyomi avoided having friends and seemed to have lost faith and trust in people and himself. (Source: Bakemonogatari Wikia, edited)

When Sasuke was young, his clan was murdered by his older brother, Itachi. With his parents and family now gone, his brother spared him and left him to survive by himself. He told Sasuke to hate him. Sasuke tried to forget about the past by applying himself in the ninja academy and fitting in with the rest of the leaf village. After his fight with Naruto, he believes he's been wasting his time "playing ninja" with the people of the leaf village. His new goal is to get stronger so he can avenge his clan by killing Itachi and then restore the Uchiha clan. As a wielder of the Sharingan (the kekkei genkai of the Uchiha clan), he learns to use Chidori and has a vast knowledge of the various Fire Jutsus. The curse seal which Orichimaru gives him during the Chuunin exam, at first, enhanced his power but at the risk of killing him. Now he can use it of his own free will. Claiming at first that he doesn't need any friends, he is forced to contradict himself when he sees that either Naruto or Sakura are in danger. Remembering this type of Sasuke is what brings motivation to Naruto. Sasuke openly admitted to Naruto that he was his closest friend. Appearance Sasuke has black hair with a blue tint that lengthens as the story goes with onyx eyes and has lighter skin than his brother Itachi. Like many other members of his clan, his hair hangs over both sides of his face to roughly his cheeks. In his curse seal form, he has grey skin with wings on his back that resemble giant webbed hands. He also has hair similar to Madara Uchiha except in a greyish-blue color. At the beginning of Part I, Sasuke's clothing made up a blue, short-sleeved shirt with a raised collar and the Uchiha crest on the back and white shorts. An interesting thing is that during Part I the Uchiha symbol on his back gets smaller each time he changes his outfit. In the last stage of the Chunin exams, he wore a black, one pieced version of this outfit but eventually went back to his original clothes. In Part II, Sasuke has grown noticeably taller (almost eye height with Itachi) and slightly more muscular. wears a white long sleeved shirt that's open at the torso with a smaller version of the Uchiha crest on his collar. He wears black pants with a blue cloth hanging from his half way up his stomach to his knees. He also wears a purple rope belt (Japanese name: Shimenawa) tied in a bow fashion found on many Sound ninja, only the bow is in a different style and is tied in the front instead of the back. He also will at points remove his shirt and hang it from his belt around his waist to give his wings in Curse Seal Level 2 room to move (also without transforming).