These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Case in point: Near the beginning of the first episode, she accuses him off being a pervert for accidentally walking in on her while she was in the shower. When Yukinari explains that it wasn't like that, she switches from accusing him of peeping on her, to taking offense for thinking he found her unattractive. So she smashes his face in, with her knee, striking him hard enough to draw blood and knock the guy off his feet, resulting in the back of Yukinari's head smacking the tub, knocking him unconscious.
No only was this completely unwarranted, she had entered Yukinari's house without telling him. Meaning, he got beaten up for just entering his own bathroom; not knowing she'd be there.
Ear Worm: The second ED, "...And Then", has an incredibly catchy beat and vocals to go along with it. Miharu is even shown skipping in tune with it.
Growing the Beard: Most people seem to agree that the second season of the anime (from episode 12) is considerably better than the first, although things actually start to improve around the seventh episode.
Les Yay: Albeit onesided from Kosame towards Kiriei.
In the 4th episode, she straddles Kirie in bed after stripping down to nothing but her unbuttoned shirt and panties, while panting and blushing about how she wanted Kiriei to be hers. And is only narrowly prevented from raping her by Lisa and her maids, who inadvertently knock Kosame into the wall, while chasing after Yukinari.
During their match in the girls fight competition, Kosame drops all pretense of grapling with Kiriei and goes so far as to lay atop her while slipping her hands under Kiriei's bra to fondle her directly.
Kosame: (dreamily, nuzzling Kirie's breasts) "Oh, Ms. Kiriei, ever since I met you, I've wanted to do this. Your skin is perfect."
Kiriei: (trying to crawl away) "Make it stoooop! Quit it!"
A later episode has Kosame chasing Kiriei around the house while calling her "big sister". Which Kiriei points out was ridiculous since Kosame was older than she isnote Kiriei is only 16 years old, while Kosame is 19. Still, after Kosame tackles her and begins happily nuzzling her cheek against Kiriei's boobs, she sighs and finally relents.
Kiriei: (mumbling, with wry grin) "Fine, you win. I'm your damn "big sister".
Memetic Molester: Kazaharu, Lisa, Hijiri, and Kosame, which unlike most other examples is pretty much canon with their personalities with the Black Comedy Rape moments they've been in.
Never Live It Down: Kirie. Most people tend to overlook the fact that she outgrows her abusive tendencies by the second season, behaves more like an actual friend to Yukinari and even has a heartwarming moment with Yukinari near the end of the series.
The Woobie: It is impossible not to feel sorry for Yukinari seeing as how the poor kid is treated like crap by his peers; has an allergic reaction which flares up if he happens to touch women, which he developed as a result of being bullied by girls his entire life. He's beaten up nearly every day by the closest thing he has to a friend, nearly all the main characters with the exception of Miharu, Koyomi, and Lisa have either used/abused him; especially Kirie. At one point, he even wonders what he's done did to deserve any of it, considering he's nice and supportive to those around him.
Woolseyism: The end of the first season has a line made more humorous in the dub where in a Hot Springs Episode, Miharu, for no good reason, gets up exclaims about a new year. Kirie, after stating it's not a new year, tells Miharu she's naked and to get back down. In the dub, Kirie actually says "Miharu, put those away."