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.
#84 Yashima and Junichi, the abused Sekirei. Remember that Sekireis, if they aren't forced by other Sekireis at the behest of their Ashikabi (Such a Higa),they will only join those they feel the greater connection to. So unless her Ashikabi was strong enough to subdue her, this means she gave herself willingly to him because he was her perfect Master. Also look ather face in chapter 25 and 26, when Junichi got angry; either she has deep self hatred and a destructive personality disorder or she loves it.
It's also possible she was in a situation like #87, Kaho but wasn't near as lucky. Note that with the exception of the various D-Squads, unwinged Sekirei apparently have a very strict "do not harm humans" clause branded into their behavior. She could have been winged as a result of a sexual assault. Does that sound "Too kinky for torture?"
Mikogami is Obliviously Evil. He approaches the Sekirei Plan as a very exciting game, and concerns himself with things like following the rules and the best ways to keep things interesting, even if doing so puts him at a disadvantage. None of his actions violate the rules, and in fact his aggressive pursuit of new Sekirei for his collection is not only allowed, but actively endorsed by Minaka when he runs the "Green Girl" and "Final Feather" events. Furthermore, his interactions with his Sekirei and anger at the mistreatment of the East's Sekirei suggest he's a Benevolent Boss.
Except for his "you have failed me" moments regarding the termination of various of his Sekirei, which were in fact (possibly) winged by force. You also have to wonder how anyone can consider forcing yourself on a child after striking down her guardian in front of her anything but evil? (Or how striking down the second in command at MBI is not "against the rules.")
Awesome Music: "Change the World", the insert song that plays during Musubi's battle with Karasuba in the 2nd season finale.
Base Breaker: Kaho, the #87 Sekirei introduced late in the manga, has become this recently due to her Spotlight-Stealing Squad tendencies at the start of the 4th stage of the Sekirei Plan when she encounters Karasuba. Almost everyone believes that she is nothing but fodder to hype Karasuba's power to make her eventual fight against Musubi more meaningful, yet the manga still ends up spending a great deal of time developing Kaho's character at this point. While some like that Kaho is being developed, others wish for the manga to simply get her character out of the way already to move on to the more important plot-points of the story.
Broken Base: Besides the above-mentioned Kaho, the Character Development of Mikogami is a source of controversy among fans. The revelation that he cares for his Sekirei, and his numerous Pet the Dog moments with Akitsu either make him a complex character or strike fans as Jumping the Shark by suddenly making him a sympathetic Anti-Villain. Akitsu's winging was equally poorly received by fans that had hoped to see Akitsu join Minato's harem.
Crazy Awesome: Minaka always had shades of this; his reason for creating and enforcing the Sekirei Plan is one part Science, one part Godhood and two parts for shits and giggles, but when he blows up his own building while still inside of it to make the game he was playing with Minato more interesting in the anime, he really does show his Crazy Awesome side.
Mikogami, since he's an obvious stumbling block for Akitsu joining Minato's harem. Discussions of his impending death, and Akitsu running off to join Minato's harem, occur literally almost every single chapter.
May have to make a new trope concerning him as it was Word of God in podcasts and the author's own blog that it was going to happen. "God changed her mind." Akitsu is now no longer "scrapped" and was winged by Mikogami. Goodbye, we barely knew you.
Foe Yay Shipping: Akitsu x Minato. Since she is technically Minato's enemy, this counts.
Game Breaker: Karasuba states that Miya and Yume are both this.
Minato. 6 Sekirei, 5 of which are among the first ten - and thus stronger than the other Sekirei as a result of not having any inhibitors (namely numbers 2, 3, 6, 8/88 (Yume and Musubi share a body), 9, and 108.). Number 1, the strongest Sekirei, is his landlady and ally, and she's actually not part of the Sekirei Plan. In short, he not only has a large number of Sekirei, but more than half of the strongest ones are on his side.
Growing the Beard: The series started out primarily as fanservice and comedy, but has developed into a more serious, character-driven story over time. It still delivers on the fanservice, but has a stronger focus on plot and characterization. This began with the Bridge Escape story arc, and has continued since then.
Karasuba, who aggressively pins Musubi to a wall and commands her to get stronger, with the handle of her sword poking Musubi in a very suggestive fashion. It's also implied that Yume is The Lost Lenore, in a very disturbing kind of way.
Ron the Death Eater: Musubi seems to be the least liked of all of Minato's Sekirei by fanfic writers, who often give Minato literally any other Sekirei but Musubi in their new harems for him, with some stories actually having her murdered to justify her not showing up in said fanfic. The main reasons for this stem from how "obvious" it seems she'll be the "winner" of any battle for his heart, and since that presents a major stumbling block to shippers, she gets written out or is often NOT the first one to meet him so fic writers can keep Minato's options open. As for her as a character, she does tend to get seen by some a Satellite Love Interest compared to the other Sekirei (in their defense, she can be rather ditzy), so that's another reason.
Shipping Goggles: Not as many fans as Akitsu shippers, but Uzume does have her fans who want her with Minato.
Karasuba is female too. The only reason its hard to tell at times is because unlike the other women she usually doesn't go out of her way to show her femininity off in public and has a fairly gender neutral voice.
Villain Decay: Benitsubasa and Haihane suffer what is possibly the fastest villain decay in anime history, portrayed as terrifyingly powerful antagonists at the end of season one, but reduced to incompetent jokes by the start of season two.
Woobie Species: The Sekirei, as a result of being forced to participate in a "game" that forces them to find their One True Love.....and then fight to the death with the rest of their kind in the distant hope that they might be the Final One, and earn the right to remain with their Ashikabi. It becomes even more cruel, since the odds are stacked against the vast majority thanks to the Single Numbers being more powerful than normal Sekirei. This drives several pairs to attempt to escape the game, only to be hunted down and slaughtered by the Discipline Squad.