Okay, let's start off with the general feel of this episode. I've liked the somewhat minimalist approach to the art direction so far, and this opening scene is this show's art direction to it's core, showing how far Nanami has come in learning and actually fighting. The part where it shows the soldier reaching for her and she just see's it as a weed, so far from her level of fighting it's not even worth looking at.
Her "catchphrase" of questioning whether something is good or bad morally shows her complete malgrowth since she has left the island, however it is also shown she's never been very morally directed in the first place, simply on her suicide path. In all honest I have no idea if everything she has done since she left the island was a plan to have Shichika kill her, and that's something we won't ever know.
Alright on to the play-by-play.
I already described a fair bit of the opening scene, however the windmills here show that a wind of change is coming and Nanami is going to be the source of this change, causing Shichika to grow even more as more than a sword. She sees the sword as similar to herself, being worshiped as powerful, where she is feared for it, which in of in itself is a twisted but no less true concept.
The scene of Nanami riding the boat with the memories of her dead parents saying how she's worthless and a monster, only for her to banish them for telling her things she's already well aware of, brings the fact she wishes to die to the viewer. That the scenes including Nanami are more base in animation, thicker lines, and brighter colors only highlight the difference in her and Shichika.
The dialogue between Emonzaemon and Togame hints at enemies that we have yet to see what's up their sleeves, collecting information for future battles after this tipping point of an episode is over. Likewise the dialogue between Nanami and Shichika (and later Togame) further separates brother and sister, showing how much Shichika has grown as a person and Nanami has grown as a weapon.
The rest of this scene is Shichika getting the **** beat out of him by Nanami. This is not a scene without impact however as it lays groundwork for a portion of the plot of this episode, as well as connecting it to the plot of last episode confirming Nanami slaughtered the Itezora clan, leaving Konayuki alone. Whether leaving a sole survivor was done accidentally or on purpose I do not know, but it certainly would have been a valuable piece if she knew Shichika had gained such morals. It also further explains how Nanami fights and learns and why, and displays the difference in skill level and interpretation of "being a sword". It displays how she is using Akutou Bita to her advantage, which comes up as a later distinctions about why a Kyotouryuu shouldn't use a sword. The fight concludes with Nanami stating her weakness without really stating her weakness.
This next scene is a fair bit more light-hearted, however with roots in the darker scene from Nanami earlier in the episode. While she was riding at night to the left side of the frame, Shichika and Togame are riding during the day towards the right.
They land and are greeted by Emonzaemon, who we are really getting formally introduced to at this point, and the JRPG look of it all is adorable. With Shichika needing to hunch over to fit into frame. Even the recounting of the complete annihilation of Gokenji Temple into a cute little game, complete with a more traditional looking anime CG to wrap up this scene.
The next scene is Emonzaemon reporting to Owari, nothing too in depth here other than showing how Owari uses Emonzaemon as a sword as Togame does Shichika.
This scene blends with another scene that shows off two of the main ManiWani heads, discussing the battle that will take place this episode, and their similar intelligence about Nanami. They're safe because 2 of them died last episode. It slightly brings back the JRPG look with them walking on a 2D scroller look, interestingly at night to the left of the frame like Nanami.
Little tiny scene showing how even hunger is unnecessary when using Akutou Bito, reinforcing how strong she is with it, but also giving the feel as if she is no longer alive. However when you think about it, was she really ever alive in the first place?
The scene displaying the crows feasting on the dead soldiers of Gokenji is best described in the scene, I have nothing to add to this.
And here we have Shichika moping. In many a protagonists, it would be boring filler to bring him out of it and save the day, but with Shichika, it emphasizes how much he has grown as a person. 6 months ago he wouldn't have been like this, and that impacts on this scene.
Following this we have Togame and Nanami speaking about avoiding the fight. Nanami speaks of Shichika as a rusting sword, letting his humanity eat away at him. She also speaks of the quest for the swords, likening it to her own quest for her sword and death, which Togame deflects. With the question of the duel, Nanami responds saying there is no reason to avoid it. Like some thing that is required, something that must be done eventually.
Part II of the Shichika moping scene, I really explained what was happening in the previous scene, but this is the "let's break you out of it" part, with a little cute from Togame. It breaks into Shichika's reasons for choosing Togame, as previous episodes have stated, swords choose their owners as much as the owner chooses them. This explanation and confession further strengthens the bond between the two. Togame teaches Shichika about defeat, something he's really never felt before. Sure he's lost, but he has never been defeated in a battle such as this, those were sparing matches, or lucky shots. The scene transitions in subject with Togame asking how far the bonds she has formed with Shichika run, wrapping up this "get out of the rut" part of the episode. The scene continues with Togame explaining to Shichika what the weakness of Shichika Hachietsu is, a weaker part of the move in which poorly chains with the rest of the combo. She further explains Nanami hid clues to how to perfect it in their first duel, with the correct pairing of attacks. This gives the viewer insight to both Nanami's twisted kindness of not wanting her brother to be killed and herself wanting to be killed "correctly". Scene wraps up with Togame saying what she's been doing during Shichika's mope, and it wraps up with a joke about Shichika being a masochist. Yeah, have you seen his sister? I would be surprised if he isn't.
Anyway, transition scene where Togame questions Nanami's motivations and it states Nanami's desire for Shichika to kill her like a swordsman would die.
TRAINING MONTAGE!!!!
Togame gives the terms of the duel. The scene reasserts the concept of a "sword using a sword", with Nanami giving backstory to her father and herself while Shichika perfects his technique via brute force method. Nanami makes a dark joke. She also tells Togame it's normal for Yusari family members to kill each other. She wants Shichika to kill her like a member of the family. Ironically, by killing her, he will show her how much she means to him, in her eyes. Beautiful art effects while Togame and Shichika face off with words and minds. Togame is a dork for the rest of this scene and we get a humorous slide out.
Okay the fight. Shichika asks a question Togame asks earlier in the episode, showing his own reluctance towards fighting his sister, his only blood family left. Nanami says to come at her with intent to kill, and Shichika readies himself without a word, knowing there is no other options. This is the point it reasserts some of the reasons for this fight.
Then it explains the fight. Togame's plan, and Shichika not liking winning with such an underhanded trick.
Nanami then get's up with a very symbolic hole in her chest and explains why she learned other people's techniques, to curb her own abilities, to make herself weaker, so someone can kill her, so Shichika can kill her instead of her own power killing her.
What happens next is SUPER important. Nanami gives Togame a haircut. This is rather important to Shichika, as we are reminded of in every episode, including the scene where Shichika confesses his reasons for not telling Togame of Nanami's strength when they met. Togame's hair was how Shichika learned to identify Togame, how he got to know her, and it's cutting is Nanami spitting in the face of that history and bond and it burns. So of course it pisses Shichika off. Which is what Nanami wanted, however, she doesn't understand the significance of her act.
The statue of Budda(I think that's something lost in translation here) turns his head, further emphasizing the importance of this fight.
As Shichika goes to strike the final blow, he shows how reluctant he is to put his sister to rest, as the blows strike her, Nanami thinks on her life, and comes to a realization, a sword should not use a sword, and her ability is a conflict with this, and hence why she cannot die yet she is so weak. Dandelion is the last technique, a flower being scattered due to it's own processes. That is Nanami.
And she ditzes her final words.
woops.
Then Togame explains what I just said.
Togame and Shichika talk about the aftermath. Shichika says how he didn't want to kill his family. Episode wraps up with a cute thing on the boat, showing that their bond no longer requires Togame's hair, and they are family, both without any family but each other.