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.
Angst? What Angst?: Much of the series is prevalent on the idea that the since this is feudal Japan after the Sengoku Period, violence is something to be taken in strides for the most part. Episode 6 cements this idea when Kawauso is told that he may have to die in order to cement an agreement for his clan. His response? "I've done a lot of things for my clan. But I've never died before."
Also Princess Hitei, who is remarkably unfazed by the death of the only two people she cares about and what she assumes to be her own impending demise.
Base Breaker: Episode 4 is notorious for pissing off large numbers of the fandom. The preview after episode 3 promises the series' first real fight sequence—a cataclysmic battle between Shichika and Hakuhei, the greatest swordsman in Japan and the holder of a beautiful sword with a glass blade. Even the setting, Ganryu Island, is the legendary ground for the duel between Musashi and Kojiro. They even show clips of crazy feats like Hakuei splitting the ocean with his sword and offhandedly cutting an entire shark in half to save Togame, and Hakuhei and Shichika's blade locks causing explosions! The actual episode is almost entirely about the strange and terrifying combat abilities of Nanami, while the last few minutes of the episode are of Togame and Shichika discussing the already won battle with Hakuhei over lunch.
"Togame" is also touchingly beautiful (and will have you in tears by the end of the anime).
Designated Hero: Played with. Shichika often seems to be a borderline villain, or at least Anti-Hero, and his quest hardly seems to be heroic. Most noticeable so far in the third episode.
His sister, Nanami is even more-so, especially in episode 4, where her phrases seem more in line with an absolutely evil individual than an ambiguous heroine especially compared to her more humane opponents.
Becomes an outright Villain Protagonist in episode 7 whose tragic backstory prevents her from being pure evil.
Togame, whose actions and desires imply that she'll use anyone to achieve her goals like a puppeteer outright confirmed to be a Villain Protagonist by episode 12.
Fetish Fuel: Togame frequently wraps Shichika in her hair as "training" to help him learn to distinguish people. Lampshaded when she accuses him of having a hair fetish.
Togame has her own fetish fuel moments at least every episode.
Foe Yay: Also counts as Les Yay with Togame and Princess Hitei in episode 8, both are very competitive and sounding more like two girls trying to dominate one another than political rivals trying to upstage the other.
Freud Was Right: Kanara develops a crush on Togame, because she reminds him of his dead sister.
"Funny Aneurysm" Moment: Togame's Clingy Jealous Girl antics in episode 9 become less funny in light of episode 12's reveal. They show that she really has fallen in love with Shichika — one of the people she has sworn to kill.
Episode 4: Once the viewer is shown via torture-and-murder of Kamakiri that Nanami is a world-class combatant and that the rest of the Maniwa Insect Squad is well and truly doomed, Chouchou decides to trip as many death flags as he possibly can in the course of a few minutes by mentioning his girlfriend, his plans to marry her after this mission, and a promise to share a smoke with Hachimitsu to celebrate the mission's successful completion. It's implied that Chouchou knew he was walking to his death, but the sudden blitz of death flag tropes is so contrived as to be laughable.
Episode 12: Togame's pre-death speech is very long. Almost ten minutes. At first it just seems to be dragging on a bit, then all the emotional momentum is thrown out the window by her odd method of distancing herself from her own emotions, i.e. claiming that she was going to kill Shichika after all twelve swords were collected and dismissing her own genuine love for him and her extensive character development as pawns to be manipulated... by herself.
Nanami after episode 6. It is shown that she may be the one who wiped out the whole Itezora clan, and most definitely wiped out the whole Shireizan.
Episode 7 confirms the above and adds the conquest of the Seiryouin Goken. And a little scene in which one of the dying guardians of Akutou Bita grabs Nanami's ankle. When she looks at him she doesn't see a person, she just sees a weed that she proceeds to stomp on repeatedly.
When Emonzaemon murders Pengin. He put the gun in his mouth... *shudder*
Viewer Gender Confusion: Rinne was once a human, originally a man, now appears in different forms dependent upon the viewer. The form we see is a half-naked little girl, complete with a strange, cute giggle.
Maniwa Pengin, thanks to his high-pitched voice and Shrinking Violet tendencies.
Villain Decay: It gets harder to take the Maniwa ninjas seriously as threats with each new episode. The first one was a skilled assassin who made good use of disguises and trickery and only lost due to bad luck. The second and third are one-shotted by the real antagonists of episodes 2 and 3. Then there's the Insect Squad... poor bastards had the bad luck of going up against Nanami. The Insect Squad even lampshade the Villain Decay; noting that the Maniwa Corp is being seen as the underdogs now.
Averted with their Leader Houou who's making up for their apparent weakness by himself.
However, by the end of episode 10, every single Maniwa Corp head besides Houou and one seriously wounded member is dead.
Lampshaded by Shichika in the final episode, when he kills the Maniwa ninja wielding Soutou Kanazuchi, he says that there wasn't really any Maniwa ninja weaker than that one — if you listen closely, you can hear him laughing as he says it.
The Woobie: Poor Konayuki, only a child and Last Of Their Kind, thankfully, she's one of the few characters remaining alive after the ordeal.