Even funnier is that when he's unconscious after the blowback from his Ittou Shura, she takes off his shirt herself, rationalizing that it will "make them even." He naturally asks what she's doing when he wakes up, and she hits her head trying to run away.
The scene between Ikki and Stella in Kurono's office is full of some good gags.
Ikki: That's a joke, right? Stella: It's no joke. I've made a great compromise. Ikki: Your compromise is for me to kill myself?!
After seeing that Ikki won't kill himself, Stella starts to go into Pervert Revenge Mode by lighting fire around herself. But by complimenting her beauty, Ikki causes Stella to disable her powers due to her embarrassment and (in the anime at least) sets off the fire surpression sprinklers above her, leaving her soaked instead. (She literally gets wet.)
When Stella learns that Ikki is her roommate, she makes a lot of ridiculous demands, like not allowing him to breathe.
When Ikki tells Stella about his sister, he mentions to her that Shizuku is his actual sister, as if to reassure her (and the audience) that there will be none of that Not Blood Siblings pseudo-incest thing going on. Only to have Shizuku glomp him to the floor and try actual incest.
Stella's fight with Shizuku over Ikki's affection after she kissed her brother in front of the entire class.
Doubles as heartwarming. At the end of the volume, Kaito Ayatsuji wakes up from his coma and listens to his daughter about how Ikki defeated Kuraudo and took back the dojo. Kaito then calls Ikki and asks him to marry Ayase and take over the dojo, much to her embarrassment.
When Ikki and Stella go to the Student Council room, it's revealed to be a complete mess of papers. In the manga version, Ikazuchi is shown holding the closet doors closed after overstuffing it with the papers.
Stella giving Akaza his just desserts is certainly memorable, to the point where someone made a gif image of the anime scene.
Stella plays Badminton with Renren. In the Light Novel, they seem to play normally. But in the anime(episode 9), They start bringing their powers into it, resulting in what a dazed Ikki calls "a great sport that's not at all badminton." While in the foreground, shuttlecocks whip past the screen, along with he occasional can, fireball, racket, and tanuki statue. Also, Renren's jacket, gloves, and shorts somehow get into the mix.
The log cabin scene. To summarize, Stella comes down with a fever while she and Ikki are in the woods, and a sudden rain shower forces the two to seek shelter in an abandoned shack. The hilarity comes in when Stella asks Ikki to help her out of her wet clothes to keep her cold from getting worse. Ikki does, but it's made clear that he's struggling against certain...urges while doing it. He nearly gets away with it, but ends up being betrayed by his own body. Stella notices, and Ikki is just about ready to die from embarrassment. It's a good reminder that beneath all of his calmness and control, he's still a teenage boy.
Shizuku is shown reading a book called "One Hundred and Eight Ways to Bully the New Wife," showing that she's not going to go easy on Stella anytime soon.
For some Black Comedy, in the afterword, Riku Misora actually lampshades Ikki's ridiculously bad luck throughout the volume.
"Generally, that would be miserable. Surely it would be like the heavens trying to kill him. Well, that's how his life is usually like, but his luck is F-rank too, right? It can't be helped."
The first chapter contains a bit of Ikki fanservice, such as how Shizuku nosebleeds upon seeing his bare chest.
Upon meeting Ikki, Sara Bloodlily (an Akatsuki member and terrorist) unbuttons his shirt to see if he's nude model material, only for Shizuku to anticlimactically take her out with one drop kick.
After the other participants force Yui Tatara to stand down, Ikki has a chat with the previous champion, Yudai Moroboshi. At the end of the conversation, Yudai reminds Ikki that he still hasn't buttoned up his shirt, and asks if he's into that kind of thing.
When Ikki and Yudai are fighting, Koume wants to leave the stadium, only for Shizuku to interrupt. She explains the ways in which she can relate to Koume's situation, including the fact that (in Shizuku's opinion) neither of them want to be a burden to the man they love. Koume starts nodding until that last part, at which point she blushes and shakes her head furiously. On top of this, Shizuku is actually disappointed that Koume doesn't also have those kind of feelings for her brother.
Ikki tries to surprise Stella from behind as a prank, only for her to instinctively roundhouse kick the space behind her. Luckily, Ikki dodged, or she probably would have kicked his head off.
Later Ikki and Stella are having a moment in his room when Sara Bloodlily shows up to paint him as a nude model. Ikki is thankful that Stella intervenes... until Sara proves that she's a world-famous artist (to a level most artists have to die to reach) and bribes Stella with a wedding portrait of her and Ikki so that Stella starts trying to strip him too!
And where does Ikki go to flee from them? He can't sleep outside, Shizuku will cause other problems, he decides against Alice, and so he ends up rooming with his brother Ouma!
Stella has to tie Sara with bandages to keep her from drawing Ikki in his sleep, causing the latter to end up in a risque position. Ikki wakes up and claims he'll love Stella regardless of her bondage fetish, only to reveal he knew what was going on all along and that he was just teasing her.
After the above, Ikki and Stella playfully flirt with each other. Ikki pokes Stella's cheek and comments that she's like a cat, and Stella responds by making cat sounds. Then Ikki's father walks in, causing the couple to become absolutely mortified.
Stella makes Sara wear one of her jerseys, which doesn't fit the latter's chest. This causes Stella of all people to have A-Cup Angst to the point where she has to look at Shizuku's chest to make herself feel better.
Edelweiss sits down with Bakuga, Rinna, and Sara for a cup of coffee, only to keep putting more sugar into hers because she can't handle the bitter taste.
Ikki visits Stella in the infirmary after the Seven Star Sword Art Festival concludes. They talk for a bit, and he asks her if she remembers what he told her in the log cabin, about why they shouldn't have sex. When she replies that she does, he promptly tells her to forget everything he said.
Stella is shocked at this, asking what happened to the side of him that refused to give in to temptation, even when she'd been naked in front of him. Ikki says that that person "died".
Right after Stella accepts, Ikki is about to make his move on her...when she stops him and asks if he "brought that". When he sheepishly realizes that he didn't, Stella reveals that she had already bought a box long in advance. The kicker? They used all of it.
Shizuku finds out Ikki and Stella had sex and reacts by freezing the hospital room they're in. In one fan translation, she states they were "Dragon Fang-ing the Ittou Shura of the Night."