Alas, Poor Scrappy: MC falls under this given what the game forces him to sit through and is judged harshly for his inactions despite being out of his control due to Monika's tampering. He's intended to be a stock VN protaganist, but most remembers that by the end of the day, he's a socially inept highschooler that hasn't dealt with something as serious like what his friends are going trough.
Were Sayori's suicidal levels of depression, Natsuki's tsundere nature and abusive dad, and Yuri's Nightmare Fetishist and self-harming tendencies always part of their original characters that Monika simply dialed up as time went on, or did Monika make those traits up wholesale? The fact that none of them seem to be present after Monika's deletion (Yuri and Natsuki actually get along, Natsuki's tsundere tendencies are more dialed back, and Sayori mentions actually waking up on time for multiple days in a row) suggests the latter...
Another possible interpretation is that Sayori is the one responsible for their changes in personality. Considering the fact that one of Sayori's defining motivations is her desire to make everyone happy, it is strikingly in character for her to try and remove or downplay the parts of her friends (and her own) personalities that make their lives difficult or cause friction. This can be supported by the fact that, unlike in the bonus ending where Monika is deleted early, Sayori seems to have a decent (okay, comparatively decent) handle on her situation, making it entirely possible that she had been goofing around with files before the "route" even started.
Possibility number 3: Sayori, who doesn't seem the type to try and turn her friends into someone they're not, saw the Character Development that the player unlocked during each girl's route (Yuri becomes less shy; Natsuki becomes less defensive) and simply wrote it back into their starting personalities. But then of course, as Sayori herself notes, that's the game pretty much finished...
Meta Possibility number 4: The game was hap-hazardly created to be your average visual novel dating sim, and, in an attempt to make the game less one-note, the developers gave the girls these traits to make them less one-dimensional without really looking into how these traits would affect them realistically. After all from Monika's Date with the player we know that she took research into a lot of real-life subjects (like depression) which also explains why she would know what impact these implications would have on the girls.
Is Monika a tragic figure trapped with the knowledge that she's a fictional character in a romance game that goes out of its way to railroad the player away from spending time with her, or just a creepy self-aware yandere who ended up corrupting and killing everyone with the justification that they're not real people, even though she's just as "real" as any of them? Instances like Sayori gaining the same medium awareness whenever she holds the club president position and Yuri's awareness of her own increasing corruption as Monika rewrites her contradict her attempts at justifying the dehumanization of her co-stars.
Does Monika genuniely believe the other characters are just code and not as real as her or is that just something she says to reassure the player and herself?
Is Yuri's suicide after her confession just a result of her being crazy (she stabs herself to death even if you say yes) or does she have a final moment of (sort of) lucidity and decide to just put herself out of her misery? Monika provides a third possible explanation: she claims that Yuri self-harms because of a sexual fetish, and says that the player character should stay away from her due to him being a trigger, which would also explain why she stabs herself even after you accept her confession; however, since Monika wants you all to herself, she has all the reason to lie to make Yuri look bad. The facts that all the gobbledegook Yuri's corpse spouts for the weekend is actually in Monika's perspective (check the history) and Monika treats you spending the weekend with that corpse as an accidental result of her "script" suggest her responsibility.
If you choose to have the player character either confess that he loves Sayori or admit they're better as friends, does he truly mean either one, or is he trying to comfort a depressed neighbor and save her?
Do the girls have free will or not? Monika is convinced they don't (and therefore that they aren't real, like her), but that might be her misinterpreting the situation because only the head of the Literature Club has full meta-awareness. The fact that the girls can have both unscripted reactions to events (vomiting, for instance) and flashes of self-awareness about their changing selves imply at least a portion of freedom within their personalities.
How much of Monika was actually pre-programmed and how much of herself did she change to appeal to the player? Did she even change herself to appeal to the player? Think about it: Monika is introduced as being the most popular girl in class, as well "smart, beautiful and athletic". She's also sweet and polite to everyone, and the player character doesn't notice any "bad" flaws with her. At least some of these traits people would find attractive. Considering that Monika was able to change the personality traits of the other girls, it seems likely she would have changed herself to be more appealing.
In one conversation, Yuri starts to explain to the protagonist that she has back problems because of her large bust, but trails off in embarrassment before she can admit that's the reason. At that point, the protagonist jumps in and suggests her back problems are due to bad posture. So, was he genuinely clueless about what Yuri was getting at, or did he realize and provide his own explanation to spare her some embarrassment?
Awesome Art: The artwork for this game, as well as the art done for the merchandise, is rather impressive.
And then there's the two uniquetracks from Act 3, when Monika deletes all the other characters which fit the respective eerieness and tragedy of their accompanying scenes perfectly.
Author's Saving Throw: Due to fanbases waifu-ing particular characters, many people were concerned about Natsuki, as her younger appearance would be considered Unfortunate Implications and make certain people into lolicons. Dan himself stated that "all of the characters were 18" (including Natsuki). This however does bring a few more questions, including what year the Dokis (and MC) are in. Then again, the characters are implied to not be enrolled in an "actual" school, as the setting is implied via meta storytelling to be a virtual illusion even in-universe, so maybe real-life rules don't apply? (It could also just be a reference to the tendency of other visual novels to claim all the haremettes are 18 even if the story would suggest otherwise.)
Originally, if the player attempted to quit the game during Sayori's death scene, the quit dialog box would be distorted. However, this effect was patched out in a later update, because Dan didn't want to punish players for trying to quit during an emotionally-distressing part of the game.
Base-Breaking Character: Monika seems to be becoming the new Sans; she initially garnered lots of fans for being a Magnificent Bastard and simultaneously sympathetic, but then detractors popped up, dissing her fans for downplaying her unsavory, villainous traits, as well as running the "Just Monika." meme into the ground. Some people also hate her for simply being popular. However, the debate is generally not as nasty given the relative youth of the fandom.
A rather large amount of fanfics and fancomics describe Yuri as a Huge SchoolgirlStatuesque Stunner. Her official height is listed as a mere 1.65 m, or 5 feet 4 inches. Then again, when compared to Sayori (1.57 m, or 5 feet 2 inches) and Natsuki (1.49 m, or 4 feet 11 inches), she can give this impression.
Draco in Leather Pants: Act 3 ended up endearing Monika to a lot of players in spite of everything she'd done to the other girls, thanks to the revelation that she isn't just a stock psychotic yandere but is instead just as friendly and polite as she'd appeared, has a surprising amount of insight into different topics, and her existential crisis leading up to that point making her more sympathetic. What really sells it is her Heel Realization which most yandere characters either don't get or simply ignore.
Ear Worm: Just try getting the theme song out of your head.
Evil Is Cool: Monika may be one of the most nightmarish video game villains in years, but damn if she isn't ultimately a well-written, stylish and innovatively unique character.
Evil Is Sexy: Monika, perhaps by her own design due to tampering with the game's code, has gained a fair few fans of her appearance. Her thighs in particular managed to attract a fair amoundet of Male Gaze.
On one hand, the usual "West vs. East" arguments go down - is DDLC a weak attempt to copy what's been already done by the Japanese, or is Totono a weak exercise that doesn't do anything with its twist and plays the tired "yandere" archetype straight for fetish appeal (a sentiment that some Nitroplus fans already had even during Totono's release), where DDLC does it in a much more meaningful, deeper, and cliché-less way?
On the other, the success of DDLC has renewed interest in attempting to translate Totono (which is hard to do so, scripting and programming-wise, as Totono also has its' own script and programming tricks to scare the player and alter their gameplay for horror that makes it difficult to alter), as well as jokes about both of the focal characters (such as "Just Miyuki"note The Monika equivalent of Totono) becoming in-jokes.
All in all, Fandom Rivalry or not, Totono ended up receiving a sizable amount of Colbert Bump from English-speaking territories enough that it was announced for an English localization in 2018.
There are a significant number of fan mods that focus on resolving one or all of the girls' issues in some way or another. Popular examples include stopping Sayori from ending her life, exploring Natsuki's relationship with her father, and helping Monika deal with her jealousy and existential crisis.
Another popular fanwork plotline is focusing on the club with all Psychological Horror elements removed and played much more Lighter and Softer than the actual game. Usually this either a "what-if" on Monika not tampering with the game or being meta-aware or more as a Slice of Life work.
A fairly common one is to focus on the game's events from the viewpoint of one of the girls. Doki Doki Rainclouds, told from Sayori's perspective during Act 1, is probably the most well-known.
Fanfic Fuel: How would Yuri and Natsuki react if they would find out that they are in a game?
Fetish Retardant: Seeing what happens to any of the girls and how they end up acting can undermine their general cuteness, attractiveness and moe appeal. Monika most of all; she has an appealing design with a taller build and Rapunzel Hair and an endearing Cool Big Sis personality, but a lot of her kindhearted moments are faked and she's one of the most supremely nightmarish elements in the game.
It gets to the point that DDLC has inspired plenty of people to try out Katawa Shoujo, leading to a small renewal in popularity for the latter. Even those who are fans of the latter but aren't into the former are pleased about its popularity because it incentivated a lot of fans to try out the latter, leading to a fresh new breath of life for the Katawa Shoujo fandom after it spent years in a figurative coma.
There's also a somewhat-friendly relationship with the Undertale fandom, since both games have a focus on both the fourth wall and the different sides of the game's characters.
Fans of [redacted] Life also actively recommend fellow [r]L fans to check out Doki Doki because of their similarities. Both are Visual Novels that play around with common visual novel tropes, have a character who is self-aware that they are trapped in a game, and have a metafiction narrative that requires the player to mess around with the game's files.
Another odd fandom friendship comes in the form of DDLC and Homestuck. This most likely stems from the fact that the main DDLC Discord server was created by users from the main Homestuck server. It helps that Hiveswapfinally released its first act around the same time that the visual novel came out.
Some fans of Hotline Miami also seem to get along well with DDLC fandom, having spawned dozens of crossover art and synthwave remixes.
A somewhat sizeable overlap exist between fandoms of DDLC and Everlasting Summer, helped a lot by similarities between the characters of Yuri and Lena. One mod for ES, "The Music Club", has a similar setup with the protagonist joining a club packed with cute girls, and features Yuri as a new character (naturally, she's the roomate of Lena) in an extended Shout-Out.
Sayori's entire characterization is this once you play through the game. She's presented as your cheerfulChildhood Friend, and has typically cute and quirky flaws you'd expect from a Dating Sim heroine; she's clumsy, she's often late to school because of oversleeping, she has trouble staying organized, is mentioned to be a Big Eater, and relies on her relationship with the PC to make sure she's on track. These aren't just stereotypical Moe traits, but signs that Sayori has been living with depression. Once she reveals this to you, it puts much of her characterization into less "cute anime girl" and more "cause for concern". It only gets worse after she commits suicide. So, it's harder to find scenes featuring her cute or funny on future playthroughs with that in mind.
The entire scene where Sayori tries to trick the MC into buying her a snack is this in particular. It's played largely for laughs, as well as showing the club's dynamics between each other. However, the PC tells her that "If you feel guilty, that means you deserve to feel guilty". This statement is a lot less light-hearted when you realize that, thanks to her depression, Sayori feels like she is a terrible person and deserves to be punished. The same scene also has the rest of the club jokingly speculate that Monika ditched them to spend time with a boyfriend. This is also less funny once we know Monika's true feelings on the player and what she's willing to do because of them.
Really, a good chunk of the first act becomes this when viewed through the lens of subsequent character reveals. Natsuki's tsundere antics take on a much darker tone when it's revealed they're an expression of insecurity driven by a bad home life and a desire for the club to be a place she can actually feel safe and secure; similarly, Yuri's Shrinking Violet tendencies are that much sadder when you learn her social anxiety has deeply isolated her and fuelled a problem with self-harm. Even Monika's statements in the first and part of the second acts can be viewed this way, as they are revealed to be her increasingly-desperate attempts to forge a connection to the player - the only other person who understands the artificial nature of the game world - when the game refuses to allow her one.
Gateway Series: Even though the game is a very non-standard twist on the genre, it introduced a lot of new players to Visual Novels, thanks to its large popularity and lack of entry fee.
Genius Bonus: Monika's description of what happens to her when the game closes is more or less how RAM works.
Heartwarming in Hindsight: The game's themes of the nature of reality and metafiction, and the nature of the characters as virtual doesn't seem to have stopped the huge portion of the fanbase that have reported how deeply they got attached to the characters and felt a connection to them as though they were real people, even wanting to create fanworks to give them a happier ending.
The premise of Yandere Simulator was once described by its creator as, essentially, "a background character in a dating sim suddenly snaps and wreaks havoc on the narrative." It's a pretty good way of describing what happens in this game, too.
The green eyes, "glitch" aesthetic and psychopathic personality is essentially a much more mellow version of Jacksepticeye's evil persona Antisepticeye. Goes full circle when Jack does play the game and brings in Anti when the twist happens.
Hype Backlash: Inevitably for a game with a 97% positive score on Steam and spreading through word-of-mouth. Some believe it's just another Visual Novel that still uses anime cliches straight (if they don't dismiss it for being anime), some dislike it for the sudden popularity of the fandom and the memes it spreads (going so far as to declare it a 'meme' game), and some dismiss its scares as cheap horror. It also has a massive hatred among the VN community due to massive overexposure and people feeling the game is vastly inferior to most VN's.
It Was His Sled: If you never played this game, but later familiarized it's actually a psychological horror game, you probably will know about those scenes of the game, in most cases due to memetic mutations: Sayori commits suicide. Yuri is a Yandere with knives. Monika is the villain and literally deletes her rivals. Also Natsuki snaps her neck.
Jerkass Woobie: Monika becomes this after her Heel Realization. Initially coming across as a monstrous yandere, deleting Monika causes her to realize the error of her ways and reveal that she didn't completely delete the other three girls, as horrifying as their deaths were. Suddenly, her loneliness and madness from knowing that she's a video game character becomes a lot more sympathetic, and everything from that point onwards (right down to the ending song) paints her in a tragic light, as opposed to a horrific one.
Magnificent Bitch: Monika is the president of the Literature Club who gains Medium Awareness through her position of power. Unsatisfied with being the one girl whom the player is unable to romance, she takes matters into her own hands, manipulating the game's files to bring out the worst traits in the other girls to make them less appealing. When this doesn't work and the player reaches the end without spending time with her, she restarts the game with fewer girls, reworking the game mechanics so the player has no choice but to choose her. When she finally gets the player all to herself, she shows herself to be a perfectly decent being who's just desperate for real attention and genuinely wants to befriend the player. When her powers end up being used against her, she immediately restores her clubmates, having kept their files' backups, and swoops in to rescue the player if her successor attempts to abuse their power as club president as she did.
Memetic Badass: Natsuki drawn in an extremely muscular weightlifter form nicknamed "Buffsuki". Powerful enough to face gods and other memetic badasses. Catchphrase: "Square up, thot."
For someone who drives a friend to suicide with mental manipulation and cyber bullying, exaggerates the second's odd hobby into a sexual addiction that drives her to insanity, and at the very least increases feelings of parental abuse for the third, Monika gets a lot of love because of her backstory and final scene, and fans tend to downplay her actions with her own logic that they were just game characters and weren't real. This goes both ways, in that she is a frightening and amoral enough character that many fans of the game ignore or downplay her sympathetic traits and Heel Realization and view her as an irredeemable monster.
Also for a game that shows how too much romantic competition can be dangerous and Dan Salvato saying each girl deserves love, there are frequent flame wars over who is "Best Girl" with people getting unhealthily obsessed over their favorite character and calling everyone else's waifu trash.
This game is known for its deconstructive twist on Dating Sims and Visual Novels. There are, however, tons of mods that remove all the metafictional horror elements, effectively turning it into a straight Dating Sim.
When it's revealed that Monika forced Sayori's suicide with the strong implication of using cyber bullying, this had some players believe she crossed the line even after her motivation was revealed.
Monika deciding to delete Natsuki and Yuri's character files after Yuri kills herself. While it's somewhat alleviated by the fact that Monika later confesses that she was unable to bring herself to completely erase them, she's still not winning any Nobel Peace Prizes anytime soon.
One scare in late Act 2 involves Yuri giving the player a nigh-illegible poem that is covered in red and yellow stains. That's bad enough, but Yuri then says that the paper is "endowed with [her] scent".
The scene where Monika starts talking to you, the player behind the screen, is quite effective, with her going as far as to use your given name... as long as your computer's name is the same as your own name. If you name it literally anything else, or aren't playing on your own PC, it falls flat.
While Yuri's suicide is overall disturbing and shocking, the face she makes as she stabs herself is unintentionally goofy looking, especially when her eyes roll over as she dies.
Never Live It Down: Despite the fact that Sayori and Yuri have their qualities (especially in Act 1), people will always make jokes about how both of them died (Sayori via hanging, Yuri via stabbing herself). Doesn't help the fact that even Monika makes jokes on Sayori's death (even Team Salvato does, such as the Valentine series of pictures where Sayori is shown tying up knots). As for Yuri's death... let's just say that there are a ton of knife jokes out there. Yuri also has a disproportionate amount of jokes referring to her infamous "pen" remark. Monika has a minor case where she is associated with literally "deleting" her rivals.
Some of the game's attempts at breaking the fourth wall can appear a bit too ham-fisted, be it player character suddenly reminding us that "It isn't a video game where you can reload" in front of a corpse of his best friendnote doubly strange, since the game very pointedlydoesn'tlet you go back and prevent Sayori's suicide, or Monika explicitly telling you not to mess with her character file... all while giving you every possible hint and instruction to do just that.
Yuri's eyes wandering off her head due to a 'glitch' can actually be unintentionally hilarious if you're familiar with Off-Model "wall-eyed anime girl" memes from other visual novels.
At one point in Act 3, Monika will refer to you by name. Not the name you gave the player character, but ''your'' name. While creepy, it also can lead to unintentional humor if the name on your computer isn't yours; she finds it by looking at the computer account playing the game. So if your log-in happens to be something like the name of a pet, a joke, a nickname for the device, or anything other than your actual name... And, of course, the moment completely falls flat if you've simply named your character after yourself.
One of Monika's poems in fullscreen pulls up a Windows 10 Blue Screen of Death. Even if you're not on Windows 10, in which case it becomes pretty self-evident what's really going on.
nitro+'s Kimi to Kanojo to Kanojo no Koi. (Or Totono, for short) follows a very similar Surprise Creepy arc, such as:
What should be a normal dating sim subverting every cliche involved (such as multiple routes, saving/loading, characters who only exist to fulfill anime cliches like the moeblob, required romances, Ms. Fanservice, the Unlucky Childhood Friend, et cetera.
A normal, everyday girl twisted into a Medium Aware yandere driven to insanity by the player's unwitting actions (in both cases, the player character choosing a girl other than themselves), the nature of which makes them realize they're a background character in a fictional game.
Said yandere realizing that the boy they love is not real, and falling in love with the player themselves.
The girl, in a fit of madness, murdering her competitor(s) in a sudden switch to Psychological Horror and destroying any attempt to go back to normal gameplay via faux-scripting and programming, horrific glitches, save file altering, destroying the other characters, and locking the game's progress to her only.
The girl rewriting the game after attempts to go down alternate routes, so the player character can only come back to them, forever and ever - in both cases, featuring an impossible, non-digetic location where the girl can have their heart-to-hearts with their beloved.
Various commentary on the nature of their existence, down to noting how long the player's been gone, and begging them to stay with them.
The girl accidentally giving the keys' to the player's freedom by way of showing them where they can do some tricks of their own to return the game to normal.
This hasn't gone unnoticed by Nitro+ themselves, as Totono's writer is currently playing and documenting his playthrough of DDLC.
This trope might be the reason why Totono was picked up for an official localization in mid-2018.
[redacted] Life, a freeware game released a year before Doki Doki, is also about a visual novel protagonist who realises they're in a game, as well as a yandere who tries to gain the affections of the player character.
The genders are flipped in it, but Senpai, Please Look at Me! is another visual novel that's described as, and initially seems to be, nothing more than a cutesy, somewhat cliched romance visual novel... until one of the game's characters is revealed to be a medium-aware character who decides that you've been spending too much time with their romantic competition and deletes them from the game so that you have no choice but to interact with them only and also causes the game to become increasingly glitchy from their constant tampering with it. The game even has its climactic scene be a conversation between the character and the player (who's explicitly different from the player character here too) that ends with the character realizing the error of their ways and atoning by reinserting the characters they deleted back into the game. It does take a significantly Lighter and Softer approach to these otherwise-similar events, though, and makes it easier for you to get a happier ending.
Paranoia Fuel: Act 3 gives a good idea of what Monika is capable of. While she can't see the player directly, she can figure out your computer's log-in name, where you downloaded the game from, and if you're livestreaming the game. It's also heavily implied she has some knowledge beyond scenes with her in them, such as the bit with her towards the end of Act 1.
The game shares some similarities with a story from another medium: the School-Live! manga. Both feature four stereotypical moe anime girls in a bright and cheery school environment, which however is just a facade for the unending nightmare they live in. And, while their personalities are quite different, both groups of girls share the same hair colors (light brown, hazel, pink and purple).
Some have compared it to [redacted] Life, a free 2016 Visual Novel about a character who realises that they're in a game and try to find a way to escape it.
The game also has a few points in common with Spooky's Jump Scare Mansion, in that they're both games with a cute animesque aesthetic that however openly and deliberately sell themselves as horror games and have a female character that talks directly to the player. And in both games the Surprise Creepy is likely not what the players think at first, playing on their expectations and lulling them in a false sense of security.
Many fans consider it to be an evolution of the Sonic.exe subgenre of horror, given that one of the characters gains control of the game and one by one wipes out the other characters by twisting both reality and the characters' minds. The main difference is that it's told from the perspective of a neutral unseen protagonist.
The game falls under a similar category of fiction to Neon Genesis Evangelion and Puella Magi Madoka Magica, as a dark deconstruction of a normally optimistic and upbeat Japanese fiction genre with a Psychological Horror twist. All three works have a heavy emphasis on cute girls meant to be endearing to the player, and the initial cutesy vibe of DDLC is very similar to that of Madoka Magica and its sequel movie before descending into darkness. DDLC stands apart from Eva and Madoka in that it's American-made, is a visual novel rather than an anime, and aims to directly disturb the player rather than merely using its shock horror elements to tell a story.
Played with when it comes to this game's Steam release. On one hand, the Steam tags list this as a horror game. On the other, the fact that tags are user created, and a number of joke tags have been done with other games, could make players think otherwise.
"Disturbing content" warnings preceding the game are an indicator that this not just a visual novel/dating sim.
Some Anvils Need to Be Dropped: The game drops a few on how properly to help others suffering from depression (as opposed to just simply telling them to "feel better"), especially with Sayori's plotline in Act 1 and this later scene with Monika:
Monika: ... If you think you know someone struggling with depression ... You can help just by treating them like they're a good friend. Spend time with them, even if they don't feel like doing much and remind them that they always have something to look forward to. Making plans in advance, letting them borrow something, or even just saying 'See you at school tomorrow'... All of those things can help your friend make it to the next day. I hope being friends with Sayori has given you some perspective on the true face of depression.
Unlike Sayori and Yuri, we don't get as deep a look into Natsuki's inner demons as the others. The second act provides hints, but she never gets to have a breakdown like Sayori and Yuri. Even Dan himself has stated that he regrets not doing more with Natsuki.
Unlike Natsuki, we never find about how Sayori's suicidal tendencies and Yuri's self-harm issues have manifested or how they started. Aside from Monika's tampering with the game. Or if there was a cause to begin with. Isn't it suspicious that we don't learn anything about Sayori's or Yuri's family life?
The MC so far is the least developed due to being intentionally relegated to stock VN protagonist. Some people felt he was wasted as a character and would've loved to learn what inner demon he has.
Some players felt that it would have been better for the story to continue in the direction it was heading before the first-act-ending twist — rather than delving into metafictional horror, it could have been a more standard Visual Novel that explored the characters and their respective mental and emotional issues with more depth and sensitivity. Think Katawa Shoujo with mental illness instead of physical disability.
Similarly, Yahtzee expressed the following sentiment regarding Sayori's depression and subsequent suicide.
Natsuki never does get a horror scenario of her own and gets deleted entirely offscreen, coupled with a less in-depth look into her mental state, some players think she was underused.
No matter what happens the player will never get to play the day of the festival, even though early on it seemed like it was once a playable day within the game. In Act 1 Sayori's suicide breaks the game and causes the festival day to be unable to load, Act 2 Monika resets the game right before the festival, Act 3 Monika has broken the game so much that there is no longer any time progression, and in Act 4 either Monika will just outright delete the game, or Sayori will give the player the Golden Ending and end the game on the first day.
Uncanny Valley: Some of the glitching after Sayori's suicide falls deep into this category. Special mention goes to the photo-realistic eyes and mouths.
Unintentionally Sympathetic: To a degree. While the player character isn't a paragon of support and has a lot of snark for Sayori in particular, he does come to care for the girls in a very heartfelt manner. He's intended to be an unlikable stock VN protagonist, but this actually gives him more depth than most in the genre. He's not just out for sex and at least in the sections that are playable, does not take advantage of the girls at all. He's a genuinely Nice Guy, but isn't always the best at showing it. And even though he's Innocently Insensitive, even when Sayori reveals her depression, he still tries incredibly hard to help and wants more than anything to make her feel better. And when she commits suicide, he's so burdened with guilt he blames himself for it. At the end of the day, he seems no worse than the average teenager put in a situation he isn't equipped to handle.
Sayori has crippling depression, and is finally driven to suicide by Monika. The portrayal of her battle with depression is very realistic: details like her difficulty finding the motivation to get out of bed in the morning, her desire to maximise everyone else's happiness because she knows so well how terrible unhappiness feels, and her guilt over the fact that even getting what she wants doesn't fix her depression, are all particularly hard-hitting to anyone who's experienced or witnessed chronic depression.
The other two girls have sympathetic problems of their own even before Monika starts rewriting their personalities:
Yuri is extremely socially anxious, to the point that she would rather shut herself down entirely than share her true personality with anyone, even cutting herself to "calm down" if she feels she's getting too outgoing and excited. Additionally, Yuri seems to be retaining awareness of her growing psychosis but being unable to stop it.
Natsuki's father is neglectful (at best) and/or abusive (at worst), and she's suffering from malnutrition because he denies her both food in the house and the money to buy her own while she's at school. Natsuki is also the most able to retain her sanity, but with it comes the knowledge that Yuri's self-harm is spiraling and that Monika is somehow encouraging it, and that she's powerless to stop it.
Even Monika, as terrifying as she is, is driven by the knowledge that she's a fictional character in a romance game and frustration that she's doomed to never be able to spend time with the player, and finally ends up destroying the game for their happiness.
Even the protagonist isn't immune, since he's just as much a victim of his nature as the girls. And then there's his reaction to the suicide of Sayori, his best friend since childhood, and possibly girlfriend, depending on if you accepted her confession. No matter what, he'll blame himself for what happened. Already gutwrenching, but even worse when you consider that it was likely due to Monika's influence... How can you not want to give him a hug and tell him it's not his fault, that there was nothing he could've done?