While under the effects of a quirk that turns him into a Bishōnen, Bakugo in an assignment rescues Midoriya from Todoroki by carrying him in Bridal Carry and asking if he is ok. He snaps back to his old personality quickly, but Midoriya was certainly not expecting it.
Bakugo: It's all okay now, little man. Tell me, are you hurt anywhere...
Recall that Ochaco wondered what Deku would do in a tough situation, and Aoyama interprets this as love. Deku had done the same thing several chapters earlier with Bakugo.
According to Lisa, the writer of the 3rd ED Datte Atashi no Hero, the songs lyrics are about Izukus honest feelings for Bakugo. Several of the lyrics are rather suggestive, roughly translating to Even if theres only one lifetime, there are many chances to be together", "Youre the strongest, giving me, with absolutely nothing, meaning in life", "When I look at your eyes, I can run too", and the title, After all, you are my hero.
Deku has a tendency to snap whenever Bakugo is threatened, from the sludge villain incident (I dont know why I did what I did maybe it was the look on (Kacchans) face) to decking All Might to save him to breaking down emotionally when the villains succeed in kidnapping him.
When Compress snatches Bakugo, Deku yells out (approximately), Give him back!; Compress responds that Bakugo doesnt belong to anyone, and Deku simply repeats the same thing.
Deku is the only person Bakugo has ever cried in front of - twice, in fact, while pouring out his honest feelings of inferiority (in Episode 8 & Episode 61).
Deku feels like he has to tell Bakugo about the secret of One For All, even though he hasnt even told his mother yet, and even he cant explain why.
Deku has a tendency to compliment Bakugo excessively, gushing over everything Bakugo does, from his determination to his winter costume (Your sheer amazingness at everything you do was so brilliant to me, it was blinding).
Its not all one sided on Dekus part, either. Early in the series before Character Development kicked in, one could interpret Bakugos constant obsession with knocking Deku down a peg as some sort of bizarre repressed crush. Of course, this isnt the healthiest example, but its still there.
It should be noted that not every interaction between the two of them growing up was all bad (not that it excuses Bakugos actions, of course.) During the second fight, flashbacks show the two of them opening packs of collectible cards together and being excited when they both get one with All Might on it, with no bullying or crying on eithers behalf.
Most fans will tell you that Bakugo has bullied Deku for all of the ten years theyve known each other. However, while his treatment of Deku has been very cruel and unjustified, the exact nature of the bullying tends to be misconstrued as Bakugo relentlessly harassing Deku, without acknowledging that Deku rather explicitly followed Bakugo around, willingly participated in activities Bakugo led, and even as a teenager still finds it difficult to say anything bad about Bakugo (he refers to Bakugo as his childhood friend, rather than the kid who used to bully me and still calls him by a childish nickname that they both should have outgrown.) For the most part, Bakugos Inferiority Superiority Complex resulted in him not wanting to be around Deku at all, and, later on, morphed into picking on him when Deku refuses to go away. This, of course, should never justify Bakugos mistreatment of Deku, but their relationship has shown to be more complex than simply victim and bully.
Deku calling Bakugo Kacchan can come off this way, since most teenage boys dont usually use -chan for anyone but lovers (-chan is usually used by children or teenage girls).
Adding onto the point above, the fact that Bakugo never explicitly tells Deku to not call him by such a childish nickname is rather strange, considering how brazen Bakugo typically is. Youd almost think that someone with Bakugos pride would be more insulted by it than he seems to be, especially since he was angrier with Sero and Kirishima for saying it instead.
The anime adds in a scene during their fight with All Might that isn't in the Manga, where Bakugo explosively punches the wall over Deku's head and leans over him - in other words, a "kabedon", a romance manga trope where the guy does exactly that (except without the explosion).
There are a few similarties between Midoriya and Bakugo and Bakugos parents - highlighted in this post. Bakugo is basically a Generation Xerox of his mom Mitsuki; Deku resembles his nervous, spiky-haired dad, Masaru; and an extra has Masaru say of Mitsuki that I just couldnt ignore her feelings, similar to a line Midoriya has about Bakugo during their second fight (check this post to see it) .
My Hero Academia Smash!! has a lot of moments where Midoriya basically stalks Bakugo (a group of them in this post), including an exaggeration of the Battle Trial Arc in "Creepypasta Fan" where he apparently knows Bakugo's pre-bedtime habits; an instance where he talks about following him around in to cafes, and him making a face that has to be censored on seeing Bakugo dressed up in a bee costume.
The second fight has Bakugo open up about his feelings of guilt for All Might losing his power, once again demonstrating some vulnerability to Deku, probably with this instance being the biggest turning point in their relationship.
Deku also demonstrates how well he knows Bakugo by continuing the fight, understanding that fighting is a language Bakugo would understand.
After the fight on the roof, Bakugo compliments Dekus fighting style, albeit in his own terse way. This also marks the point when its very clear that Bakugo has moved on a bit more when it comes to his animosity towards Deku.
There is also the infamous moment when Bakugo wins the fight and pins Deku to the ground in an, um, suggestive way...
The second film is full of moments between them, from Midoriya grabbing an irate Bakugo during a confrontation from behind on the chest, to many scenes of intense stares accompanied by clips from their second fight about being "winning to save/saving to win" heroes, to looking after two kids that look remarkably like them, together; to the climax of the film, which involves sharing blood through dramatic hand holding to pass on One for All.
This video outright describes the two as acting exactly like exes, with Bakugo being distant and not opening up to Deku, but Deku still acknowledging him as someone important in his life and constantly saving and praising him despite his worst traits.
Midoriya is the person whom Todoroki is the closest with. They develop a mutual respect and they seem to have become each other's confidant. During their first battle, All Might wondered if Midoriya might have been trying to save Todoroki (from himself, most likely). All things considered, it looks like Midoriya succeeded.
As time goes on, they appear together more often, Midoriya seems to like to chat with Todoroki and invite him to the class' get-together.
This post analyzes shows how Midoriya and Todoroki's relationship progressed through the manga and, although it was made by a shipper, so it's biased, they correctly point out that Todoroki's bond with Midoriya is very important to him and that Todoroki developed a soft spot for Midoriya.
Their relationship post Sports Festival is pretty much a Heartwarming Moment every time it gets the spotlight. Specially considering that Midoriya is all but stated to be Todoroki's first friend.
At the times that something happens to the class, Midoriya often ends up looking for Todoroki to see if he is okay. It's one of his first instincts.
In the second movie, as Todoroki passes out from his own cold snap, he murmurs "Midoriya..." even though Midoriya isn't even there.
Iida trying to stop Midoriya from going with Todoroki, Kirishima and Yaoyorozu to rescue Bakugo, the words used and a few of the scenes could be intepreted in many ways, if it was taken out of context, particularly when Iida asking if his feelings are getting to Midoriya.
The light novel has a particularly sweet scene of Iida covering Midoriya with a blanket after the latter sleeps without it.
An interesting parallel is that Uraraka, who does has a crush on Deku, looks up to him in the very same way that Iida does, and speaks about him in a similar manner too.
An image in Smash!!◊ has them laying side by side in a koutatsu. With Iida being particularly happy about it.
Midoriya and Uraraka both sleep on Iida's shoulders in the Season 3 ED. Though this one verges into Threesome Subtext.
Mirio is oddly physical with Midoriya. This is specially noticeable, because he doesn't tend to touch much Tamaki and Nejire, who are his close friends, yet, a little while after they meet he hungs his arms around Midoriya and pulls him close when they talk to All Might.
Mirio makes it clear that of all Class 1-A, Midoriya was definitely the one to grab his attention, enough so that he made sure to check out on Midoriya while they were alone on the back of the dorms and automatically look at him when they entered Class 1-A homeroom.
The scenes where Midoriya and Mirio show Eri around the school can be interpreted as two doting fathers with their daughter. In fact, most of the time they interact with her together, it seems like this.
After the events of the internship arc, Aoyama starts acting strangely around Midoriya, from feeding him some of his French cheeses to lurking at his bedroom window at night and leaving vague messages. This led some fans to speculate that this may be a case of Stalker with a Crush on Aoyama's part.
Shinso's declaration of how excited he was to fight Midoriya again in chapter 212 has undertones of this.
If one notices, Midoriya is the only person that makes Shinso smile in his time at U.A.. Most of the time, he looks serious and stoic, but he smiled at Midoriya after their fight both in the Joint Training and the Sports Festival.
Stain and Shigaraki, while it crosses into Foe Yay or even No Yay, certainly show to have become fascinated by the boy, with his quirky way of thinking and his heroic attitude. Stain lets himself be caught just to save Midoriya and Shigaraki causes a ruckus and basically holds the mall hostage just to meet him in person.
Kirishima's interactions with Bakugo can be viewed as this, given his status as the only member of his class genuinely interested in befriending Bakugo. On the flip side, as shown in Chapter 90, Kirishima is the only person who Bakugo is willing to be rescued by, something that Deku is aware of and utilizes in his rescue plan.
Worth pointing out that at the start of this arc, Kirishima was declaring that Deku was the one who could save Bakugo ("Your hands can still reach him!"). Cut to several chapters later, and we have Deku saying that it has to be Kirishima who reaches out to Bakugo. Kirishima is even described as the 'key' to rescuing Bakugo, and the chapter itself is titled "Taking His Hand" (going by the Fallen Angels translation). On top of that, Bakugo, perhaps the least cooperative character in the manga, knows exactly what to do the minute he sees Kirishima reaching out to him. No wonder the slash fans went nuts when this chapter came out.
Chapter 91 gives us Bakugo's inner monologue saying that "for some reason, my body no longer felt fatigue," accompanied by an image of his and Kirishima's hands reaching out to each other. Remind you of anything?
The Ho Yay just keeps piling up between these two. In Chapter 98, Aizawa gives a rather harsh lecture to the class proclaiming that if it wasn't for All Might retiring, he would have expelled most of them for allowing Kirishima, Deku, and the others to save Bakugo by themselves. The next panel focuses on Kirishima's guilt-ridden face and then shifts to one of Bakugo giving him a look. After Aizawa's done talking, Bakugo takes Kaminari into the bushes and forces Kaminari to exceed his Quirk's wattage limit so that he's a babbling moron. While everyone is distracted by Kaminari, Bakugo then goes to Kirishima with a handful of his own money and tells him to take it in a manner very akin to a Tsundere. Kirishima is baffled at first until he realizes the money is to make up for the 49,000 yen night vision goggles he bought in order to rescue Bakugo. In his own way, Bakugo is trying to cheer Kirishima up by giving him back money Kirishima spent earlier for the mission to rescue Bakugo. Bakugo trying to cheer someone up in this way is really unusual.
In chapter 142, when Kirishima got beaten to pulp despite being in Unbreakable Mode that he just made the first thing he recalls was Bakugo's words to him stating that "if he refused to go down, then he must be stupidly strong" in the amidst of battle which shows how important Bakugo's words are to him.
In a Halloween spread for My Hero Academia Smash!!, a half-naked Bakugo is dressed as the Big Bad Wolf... while chasing a gleefully "Kyaa!"-ing Little Red Riding Hood Kirishima, skirt and all. Horikoshi re-tweeted this picture.
The dragon listened carefully as soon as he said those words and suddenly morphed into the appearance of a young man. As the others cried out in surprise, there stood before them a young man with red hair who was smiling.
Kirishima: "Me? Im half dragon half human! The names Eijiro. Its not going to be a problem if I come along looking like this, right? Anyway, lets get along!"
Eijiro, brimming with courage and bright personality, lost against a one on one duel to Katsuki and ended up becoming his servant as a result.
Also from the light novel, Bakugo and Kirishima's study session also reads like a chaste date to some. When Kirishima struggles in math Bakugo asks him if he even knows how to do multiplication Kirishima yells in the library embarassing himself. This causes Bakugo to 'let out a genuine laugh.' Kirishima pays for their drinks in the cafe and also defends Bakugo from his middle school friends, saying 'being with him feels really nice.'
And now again in Chapter 92 from My Hero Academia Smash!!, Bakugo, while affected by a villain's Quirk that makes him act like a Bishonen from a Shoujo Manga, flirts with Kirishima during a training exercise (Bakugo acting as the hostage and Kirishima as the villain) to which Kirishima flirts back.
Bakugo: "You can try and tie me up all you want... but you'll never be able to tie down my heart!"
Kirishima: "Interesting! A challenge to see which of our hearts will submit first!"
The movie, Two Heroes, has some fun sprinkles of Ho Yay between them. Not only did Kirishima tag along with Bakugo to I-Island, they even shared a (very flowery decorated) hotel room with one bed and Kirishima was the one who brought Bakugos formal wear, which is decorated with roses. Said formal wear also includes a tie, and Bakugo hates wearing ties...but he ends up wearing it anyway.
In a battle against two villains, Kirishima saved Bakugo from an attack and gets thrown right into a wall as a result. Its probably the first time Bakugo seemed actually worried for a classmate. Bakugo even thanks Kirishima for saving him, albeit begrudgingly. Which Kirishima blushes at.
On chapter 253, Kirishima praised Deku for being able to control Blackwhip, after which an annoyed Bakugo threw his pointy mask at him. While Bakugo getting annoyed by Deku is the standard at this point, it isn't hard to interpet it as Bakugo being jealous over Kirishima complimenting another guy.
In the second movie, when Mineta calls out Bakugo for not answering civilians' requests for assistance and Bakugo retorts that someone has to be at the help center in case a villain attacks, Kirishima can be seen resting his head on his arms and looking at Bakugo in a way that can easily be described as lovesick (watch to the end of the clip).
Due to a translation of chapter 126, All Might's dialogue makes it look like that he and Sir Nighteye were actually lovers during the time that the latter was his intern, possibly with a Lover and Beloved sort of relationship which ended in a bad break up, and because of that, it would be awkward for All Might to attempt to get Midoriya an internship with him. Although it has been pointed that it might be a mistranslation, some fans think it would be weird for it to be awkward just because they stopped being co workers.
All Might: "We broke up, so it's kinda awkward." Present Mic: "Lettin' your feelings get in the way, All Might!"
Even the actual reason- that Nighteye was upset about All Might continuing to put himself in danger after his fight with All For One and Nighteye's prediction that All Might would die in six or seven years- can be seen in this light, with Nighteye getting unusually upset because the person he cares about most is in danger.
Futhermore, an Urban Legend of Zelda was spread shortly after the chapter that Horikoshi would have confirmed All Might to be bisexual in a statement. While this has been largely disproven, some people still believe that All Might is bisexual and especially that the statement implied he and Nighteye were indeed romantically involved.
All Might laments that he can't connect or make a good impression with Aizawa, and Aizawa makes clear he doesn't really has a good relationship with him and doesn't like his flashy style, but hides a respect for him. In Smash!!, when Aizawa mentions to Izuku about the feats of All Might and praises his heroics, All Might is listening in hiding, and blushes over the praise like if he has a crush on Aizawa.
Mirio and Amajiki get a lot of this thanks to being very close childhood friends that are a constant source of inspiration for each other. It helps that Amajiki calls Mirio the Sun and Mirio names Amajiki Suneater, which is really easy to make into an Accidental Innuendo. Chapter 152 shows that Amajiki can apparently feel when something bad happens to Mirio. Mirio was also very visibly distressed when Tamaki was shot by a bullet.
Amajiki spends the entirety of Chapter 159 holding an unconscious Mirio, even when he's confronting Chronostasis and surrounded by other people who could help. At one point, he even uses a Bridal Carry.
Shoji and Tokoyami's relationship started having this from the Traning Trip onwards, particularly, Tokoyami's reaction to Shoji losing a fake arm was to completely lose control over his powers and go into a murderous rampage, in an extreme vein of a Violently Protective Girlfriend.
Although it's played for laughs, one volume of the Smash!! side comics show a story where Bakugo gets hit by a quirk that makes him act similar to 80's animes Bishōnen, full on with an Ambiguously Bi vibe and Large Ham attitude while naming attacks.
In the very first comic, he attempts to pin Aizawa against a wall.
Bakugo: Dawdling before the main event, are you sensei? Let's save chit-chat for after we start lessons, why don't we?
All Might puts the class in a exercise where everyone gets a turn at playing Hostage, Villain and Hero in a hostage situation, while as a Hostage to Kirishima's villain, he ties himself down and teases Kirishima to attempt to tie down his heart.
One of the drama CDs has a villain use his quirk to stick Bakugo and Todoroki together. He proceeds to take pictures while making them get increasingly close and touchy-feely, much to their embarrassment. He even pushes their heads together to make it look like they're kissing.
There's also a sequel where that villain's brother gets revenge on Bakugo and Todoroki by doing the same thing, only this time he makes them freeze on the spot and even starts cutting off their clothes. And it's implied the two criminals have a sister...
On the subject of Todoroki and Bakugo, the Remedial Course retake arc has Camie creating a flirty illusion of Shoto to distract one of the girls. Bakugo bursts out laughing and teasingly calls Todoroki "Dreamy boy" several times.
In the second movie, as Todoroki is passing out, he whispers "Midoriya...Bakugo" very dramatically.
While it's subverted later, Twice first meeting with Chisaki makes it look like he has a crush on him. Considering he's an Expy of yours truly, it shouldn't come as a surprise if we learn that copy cat is bisexual.
Twice shows a lot of affection and comradery with Giren during the Meta Liberation Army arc. Twice feels very indebted to Giren since he introduced him to the League and gave him a place to belong; as such he is the most adamant of the League to save Giren from the MLA. And when he finds Giren he laments that the MLA removed the fingers of his right hand since it's the one Giren would smoke his cigarettes with which is a pretty intimate detail to know. Giren for his part seems to have a lot of faith in Twice, telling him in a flashback that if he could get over his trauma he could take over the entire country, laughing in the MLA's face once Twice starts going all out, and apologising for inadvertently revealing valuable information about the League to its enemies when Twice finds him believing that he failed as a broker.
Monoma seems unusually excited about having Shinso on his team during the Joint Training Arc, saying he likes him after his initial speech about not being there to make friends and calling his performance in the first match "marvelous" (even though he was on a team with class A). In one panel it looks like Monoma is literally throwing himself at Shinso, gleeful and arms open wide.
Speaking of Shinso and the Joint Training arc, some have also noted Kaminari's behavior. While everyone else is saying they're excited to work with him, Kaminari says he 'looks popular with the ladies' in a way that could be seen as flirty. Then there's him outright saying 'I like you, man' in Chapter 196 (as a gesture of admiration), and making a lot of gushing compliments on Shinso's performance after the match.
A lot of how amazed Hawks is about Endeavor comes off as a the former having a Celebrity Crush on the latter. Their lunch together can also come off as rather date-like. Helped by the fact that Hawks has essentially become Endeavor's most prominent Morality Pet.
Jiro and Momo have quite a bit of this, to the point where many fans are wondering about Jiro's sexuality:
During their first fight together, Momo rips off her shirt, exposing her breasts to Jiro, who looks between embarrassed and marveled at the sight.
Jiro becomes Momo's closest friend in the class, and is the first to attack anybody who is about to hurt her feelings in any way.
Jiro has the highest rank in the midterms (7th) out of everyone who studied for the finals with Momo, apart from Ojironote While Ojiro was 8th, Sero was 17th, Ashido was 19th and Kaminari was in last place so while she could benefit from Momo's help, she didn't need it nearly as much as the others. That, and the fact that she was the first to ask to study with Momo, after Momo invited Kaminari and Ashido, can be read as her looking for an excuse to hang out with Momo.
There are a few scenes/panels were its just the two of them, such as when everyone went to the mall and Momo asked Jiro to accompany her to the clothing store, that has bubbles in the background typical for lovers being lovey-lovey.
The Third Seasons ending has one such paneled scene of the two playfully pushing on each others backs.
In the 4koma spin-off Watashi no Hero Academia during art class when everyone is asked to draw each other's faces, Momo and Jiro both mention that its kind of embarrassing while blushing.
In the light novel, Jiro is particularly concerned about making a good impresson on Momo's mother when she comes to the study session at Momo's house.
Tsuyu and Ochaco, who even decide to walk holding hands during the Training Camp Arc, granted, it was for them to not get lost.
It's worth noting that high school girls holding hands with close friends is very commonplace in Japan.
Ochaco and Tsuyu are also on a mutual First-Name Basis with the affectionate "-chan" honorific, even though Ochaco uses last names on most of her classmates besides Tsuyu and Deku (for example, she calls Yaoyorozu by her last name, with the more respectful "-san" honorific) When Tsuyu was feeling guilty about what she said to the five people who went out to rescue Bakugo, she approached Ochaco off-screen and apparently asked her to tell them she wanted to talk with them, implying that Ochaco may be Tsuyu's best friend in Class 1A.
In a Drama CD, Tsuyu says Ochaco is "so cute" and makes her flustered, with even a blush.
A Foe Yay example between the two previously mentioned and Himiko. Himiko shows a very creepy interest in both, particularly, her dialogue towards Tsuyu looks like she is starting to crush on her, and even wants to call her given name.
During the Meta Liberation Arc, Himiko mentions that she wants to become the things that she loves and mentions Ochaco along with Stain and Deku as some of the things she loves. Later on during her fight with Curious she transforms into Ochaco and evolves her Quirk to the point that she can use Ochaco's gravity powers which she attributes to her overwhelming love allowing her to evolve.
In the anime, Mina describes Jiro's singing voice as being "husky and sexy".
Nejire and Ryukyu show to have a rather close relationship. Nejire is very clingy towards Ryukyu, and even runs to hug her at Sir Nighteye's meeting, which her employer is very receptive to, even opening her arms to get her, she also seems to value Nejire's opinion very highly, enough to hire Tsuyu and Uraraka as interns on request.
In the character profile for Yuyu, Nejire's best friend, it says that Yuyu likes cute things and thinks Nejire is "the cutest thing in the galaxy".
Two nameless civilians in Episode 67 of the anime—a Cat Girl and a girl with rabbit ears—get excited when they see Midoriya and Mirio on patrol. With the way the rabbit girl is holding on to the cat girl's arm and how close they generally seem, it's very likely that they're a couple out on a date.