While the anime versions of Monogatari Series light novels generally stay relatively true to their source material, like all adaptations, there is cut content and a handful of notable changes.
In general, the novels feature extended conversations and hefty narration commentary, while the adaptations have shortened dialogue and unique visuals. Occasionally, text flashes are put in place for narration and other text from the novels that is left out. Major plot points are mostly unchanged, though some story content is occasionally cut from the adaptations.
The novels are also notably more meta, featuring even more references to other anime, manga, and light novels and a self aware attitude in which the fourth wall is constantly broken. The novels even reference the anime adaptations, noting how certain parts may be hard to animate and mentioning voice actors of characters.
No male characters, including protagonist Koyomi Araragi, are depicted in novel artwork, so their appearances are more open to the imagination in novel canon. As such, visual gags such as Koyomi's expressive ahoge are only present in the animated version.
- Shortened dialogue.
- Little to no narration is present in place for mostly visual story telling in the adaptation, compared to the novel which is heavy on narrator commentary.
- Eikou Cram School is merely an abandoned building with no blatant signs of ruin, with working lights and elevators. In the novel, it is described as being severely worn down, similar to how it is in other adaptations. Koyomi even notes how he knows an elevator he found doesn't work, whereas he first appears leaving a working one in the opening scene of the first film.
- Background information and additional characterization for Dramaturgy, Episode, and Guillotine Cutter is mostly left out.
- The novel is more self aware, commonly comparing instances to anime tropes.
- Crows are commonly featured in multiple scenes whereas they were never described in the novel.
- The first film opens with the sunlight scene from Chapter 004 in place of a monologue in which Koyomi Araragi discusses his regret with having to tell the story. The scene features long moments of him walking around the cram school and climbing stairs before finally being set on fire. After the opening credits, the film continues with Chapter 002 and onward.
- Foreshadowing dialogue in which Koyomi describes wanting to be a plant with Hanekawa is left out.
- The sound of a car crashing can be heard during Koyomi's first meeting with Hanekawa in the film. Koyomi is seen passing the car before he starts throwing his bag in delight. In the novel, he describes being happy, but doesn't physically show it.
- Kiss shot is found in a subway station at the end of a blood trail in which Koyomi follows. Along the trail, there's also an area with a large blood splatter on the wall. In the novel, she's merely found outside under a street lamp without the intense build up.
- Karen and Tsukihi are mentioned and have indirect dialogue with Koyomi through his phone in the novel. He explains how he'll be gone for a while on a journey of self discovery.
- At the end of Chapter 004, Kiss shot is described letting out a gruesome laugh after welcoming Koyomi "to the world of darkness." In the film, she merely states the line in a seductive why while smirking.
- In the film, the vampire hunters find Koyomi in an industrial setting, unlike the novel where the scene takes place in a suburban street. Dramaturgy also threateningly destroys a large tower in the film, causing Koyomi to fall over.
- Dialogue between the vampire hunters when they find Koyomi is replaced with demonic gibberish, possibly to represent the foreign language Dramaturgy speaks in the novel and make the scene appear more frightening in Koyomi's perspective. This dialogue mostly involves: Dramaturgy speaking a different language and needing to be corrected into speaking Japanese, the hunters discussing the rarity of Kiss shot creating a minion, how he should treated as a separate bounty, and who should attack him first in order to find out about her whereabouts. After Koyomi's plea for mercy and a moment of silence, the novel also has the hunters briefly come to an agreement to attack at once before charging at him, while the film shows the hunters slowly commencing the attack without discussion.
- The second film opens setting the scene for the Dramaturgy fight from Chapter 008. In the film, the scene takes place during a heavy thunderstorm. Dialogue in which Dramaturgy requests Koyomi to join his clan of 53 vampires instead of fighting is cut. Dramaturgy implies that he is "number one" in his clan, but if Koyomi joined, he would become the new "number one" in no time. Koyomi denies and also attempts to tease Dramaturgy's for his lame invitation, saying he'd never pick up a girl in such a way. The joke doesn't land, much to his dismay. After the opening credits, the film proceeds with Chapter 007.
- Koyomi's stuttering when seeing Hanekawa for the second time is represented by the line being repeated like a broken record.
- A line where Hanekawa suggests talking about how to get rid of bullying is expanded upon in the novel, whereas the film cuts out the full conversation. Koyomi suggests using security cameras in all school rooms, to which Hanekawa criticizes for the issue of privacy. He attempts to fix his claim by stating that he'd do the honors of checking the girls locker room footage, to which she calls him out for suggesting peeping.
- When Koyomi rejects Hanekawa in the film, she shows more signs of her feelings being hurt, whereas she mostly keeps a vague smile in the novel. A line where she apologizes to Koyomi for making him say all that in order to keep her away is cut from the film.
- The novel describes Dramaturgy immediately punching Koyomi's arm "to smithereens" after agreeing to start the fight. In the film, there's first a moment in which Dramaturgy slowly walks towards him as Koyomi attempts to intimidate through boxing jabs. Instead of punching his arm off, he uses his leg to kick it off. The arm also doesn't immediately disappear, but flies across the air and lands on the floor in the background.
- The novel describes Koyomi's arm regenerating and appearing again without him noticing until he picks himself up after tripping. He then does a back flip in excitement after Dramaturgy asks him if he's done running. In the film, Koyomi's arm remains cut off as he runs away through the school and its classrooms after Dramaturgy tosses him into the building through multiple windows. He hides during the comment Dramaturgy makes and realizes his arm is starting to grow back, with a small hand coming out of his shoulder (depicted in a somewhat comedic fashion with baby giggles playing in the background). Instead of doing a back flip, he grabs the hand and pulls it out confidently, causing the rest of his arm to regenerate on the spot.
- Koyomi attempts to attack Dramaturgy head on at this point using Aikido techniques that put him in a hold on the floor. In the film, he runs away to the rooftop of the building and attacks Dramaturgy from behind to initiate the tackle. After Dramaturgy cuts off Koyomi's arms to escape with his swords, instead of running away standing up, Koyomi quickly drags himself across the floor with his legs while dodging Dramaturgy's attacks before his arms come back, causing him to crab walk and leap backwards off the rooftop.
- Dialogue between the two during the scene, including taunts and remarks about him improperly fighting like a human instead of a vampire, is cut out.
- Dramaturgy evaporates into mist in the novel after admitting defeat. In the film, the scene merely cuts to morning with the rain having stopped and Dramaturgy disappearing from the shot.