Koyomi Araragi

Koyomi Araragi  is the main protagonist of the Monogatari anime and light novels and the most frequent narrator.

Koyomi 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. Since then, he's been affiliated with Shinobu Oshino, the vampire that had attacked him, and continues to feed her his blood. As such, he's still not entirely human and certain vampire traits remain, such as regeneration.

Appearance
In the adaptations that depict him, Koyomi is shown to be a young man with black hair, grey eyes, and a medium complexion. His hair commonly covers his left eye, though it covers his right in the Kizumonogatari films. After Koyomi Vamp, he decides he should grow out his hair more to hide the bite marks on his neck. While it doesn't always seem entirely consistent, his hair does generally seem to get longer over the course of the chronological order in the anime adaptation, with Bakemonogatari featuring relatively short hair, Tsukimonogatari with slightly longer hair, and Hanamonogatari with considerably long hair.

If not wearing his school uniform, he dresses casually, often clad in a hoodie and jeans. As noted by his sisters, his fashion sense is far from admirable. A feature unique to Koyomi and his sisters is a very expressive ahoge, which often mirrors emotions.

He's quite physically fit as a result of becoming a vampire, though it's normally only noticeable when he doesn't wear a shirt.

Personality
Koyomi is a laid-back individual. Prior to his experience during his last spring break where he met Tsubasa Hanekawa, he was rather anti-social in high school, claiming that having friends would "lower his integrity as a human," due to a negative experience during his first year. This ideology seems to have multiple implications, as his explanations seem to change slightly in different instances. In Koyomi Vamp, he describes it as an idea that being close to others could ultimately harm him. If his friends got hurt, he would also be hurt. It gives a person more weak points. In Ougi Formula, which describes the scenario that birthed this expression, explains it in a slightly different way. Instead, it shows how he found disturbance in the fact that a "truth" can be made just by numbers. Something doesn't have to actually true, but if a majority of people says it is, it's treated as such. He has his own sense of what's right, and doesn't want to be a part of the "majority rule" in deciding justice. In either instance, both explanations support isolation and the idea that he would be stronger as a person if he was alone.

His experience with Hanekawa caused him to open up and be more open to making friends. He's a poor academic student, close to failing every class except math. At home, Koyomi is the only person who thinks that his family relationship is bad, while his younger sisters, Karen Araragi and Tsukihi Araragi, believe differently.

It is revealed through conversations that he's quite knowledgeable on anime as noted by Nadeko Sengoku, who appears to be a bit of a closet otaku. Other characters, Mayoi Hachikuji and Hitagi Senjougahara especially, seem to speculate that Koyomi is a lolicon.

Koyomi has a desire to help those around him and believes strongly in taking responsibility for personal matters that he could have helped despite not being any of his business. This desire causes him to behave recklessly or abuse his regeneration powers when faced with dangerous situations. Koyomi's desire to help is often portrayed as his own selfish desire and seen by those around him as being too soft towards other people.

Abilities
Powers and Abilities: Superhuman Physical Characteristics, Shapeshifting, Immortality (Type 1 and 3), Regeneration (At least Mid-High, Vampires of his level are able to regenerate from being reduced to ashes), Enhanced Senses, Absorption, Healing (Vampire blood and saliva have healing properties), Cloth Manipulation, Adhesivity, possibly Corruption, Resistance to Death Manipulation (Vampires can recover from Kokorowatari's induced death through sheer regeneration)

Attack Potency: Small Building level+ (He can easily break concrete walls with his bare hands. His jumping strength cracked the sports field. Physically superior to Episode whose cross can do this much environmental destruction.)

Speed: Superhuman (He managed to cross the schoolyard to catch Hanekawa before she could even fall over. He is far more agile than he was as a human, capable of running 100m in 5 seconds with only a slight amount of vampirism.)

Lifting Strength: At least Class 5 (He can throw shotput like a baseball. In fact he found the shot put ball to be too light. The balls thrown by him had enough power to deeply dig the ground around him. He can easily lift a concrete roller with one arm. He is physically superior to a guy who casually carries around a large cross made of thick mass of silver which is several times bigger and heavier than him.)

Striking Strength: Small Building Class+

Durability: Small Building level+ (Tanked this punch when at less than a tenth of his peak strength. His extreme regeneration and immortality makes him very difficult to kill.)

Stamina: High (His regeneration further compliments his stamina.)

Range: Standard melee range normally, much higher via shapeshifting

Standard Equipment: None notable

Intelligence: Average normally but in certain situations he can be extremely brilliant.

Weaknesses: Sunlight causes vampires to catch on fire. Weak vampires will turn to ash instantly, while stronger ones can last longer. Once a vampire is out of sunlight, the flames immediately disappear and no burn marks are left on the body or clothes. Also is averse to crosses, weakened by garlic, and gets melted by holy water. On top of this, can't swim in normal water due to being a vampire.

Notable Attacks/Techniques:

Regeneration: As immortal beings, most injuries have little significance to vampires due to their intense regeneration skills. While the speed depends on the vampire, almost any injury can be healed within minutes. If a body part becomes decapitated, it will evaporate and begin to grow back from where it was cut off. In addition, application of vampire blood or saliva can also heal wounds on humans. Seishirou Shishirui the first minion of Kissshot was able to regenerate from nothingness after his failed attempt at suicide by jumping in front of sunlight albeit it took him several centuries to recover fully so Koyomi being Kissshot's second minion should have comparable regeneration. Like other vampires, Koyomi will burn up in sunlight. This is painful, but since his regeneration is so strong he can't die from it. Koyomi's regenerative powers are so strong he's perfectly fine if his body is actively burning. His pulverized arm heals instantaneously. Instantly regenerates his hands after they were chopped off. Gives himself impromptu brain surgery with his bare hand. Revives Hanekawa from death with his blood. Instantly regenerates from having his head destroyed. Seishirou Shishirui was able to regenerate completely from just a severed piece of his hand. Kissshot regenerated and flew back to Antarctica after 3/4 of her body was destroyed. Koyomi should have comparable regeneration to both of them also even if he is disintegrated he can literally regenerate from just his ashes. However, this takes time and is thus not applicable for combat.

Shapeshifting: Vampires can shape-shift their bodies. Dramaturgy uses this ability to forge his arms and legs into swords for combat, while Episode transforms into fog. During one fight, Koyomi Araragi uses this ability to turn his arms into tree branches, but doesn't find himself capable of anything further.

Ceiling Walking: Vampires can stand and walk on ceilings as if they're on the floor. Shinobu sometimes does this in Araragi's room. After becoming a vampire Koyomi theorizes that he is able to run on walls.

Night Vision: Vampires can see in the dark.

Enhanced speed, strength and agility: Not a specific ability, but vampires clearly are far more powerful than humans. After becoming a vampire Koyomi was able to easily jump over 20 meters and while doing so due to his strength he cracked the sports field, still this is nothing compared to Kissshot who in her prime traveled all the way from Antarctica to Japan with a single jump, the recoil of which nearly destroyed the continent of Antarctica.

Trivia

 * Araragi is not depicted in the light novels' illustrations. Most character designs are based off of the light novel illustrations by VOFAN, but his character design was created by Akio Watanabe, who supervises the character designs for the anime series. Later appearances such as in manga adaptations base his appearance off this design.
 * The kanji for his given name (koyomi) means calendar. Likely to reference the wordplay, the Koyomimonogatari app that distributed the anime adaptation of the same name features calendars.
 * While there is no direct or canonical narrative reason for his hair being slightly different in Kizumonogatari, it could likely be meant to represent his difference in personality in the story. Theoretically, he could have started covering his left eye instead of his right after the events of Koyomi Vamp had changed him.
 * It seems he still has vampire fangs although it's not shown much. The fangs are visible in Episode 1 of Bakemonogatari when he's about to pull a staple from his mouth.
 * Later in the series when the two come to terms with each other, Shinobu Oshino commonly refers to him as "Omae-sama." In the old Japanese, the word "omae" was formal. So that's why Shinobu who had visited old day's Japan said old Japanese and use "omae" as if it was formal.
 * Koyomi has a fetish for short-haired girls; a fact that caused Tsubasa and Hitagi to change their hairstyles during summer vacation. While likely not necessarily related to his fetish, almost all heroine characters besides Mayoi are also depicted with short hair at some point in the series. The change in hair style is typically used as means to display change and or growth in their character.
 * In early 2016, Araragi won the second annual best guy voting contest on the subreddit r/anime.