So here's a brief out-of-memory-only summary which isn't all too detailed unfortunately due to my nearly-nonexistent japanese comprehension and the fact that I had to watch the raw in a hurry, without time to rewind. Omni, please get well quickly!
Almost everyone is leaving the Strawberry Dorms for summer vacation. Chio takes the leave-taking from her precious Nagisa-oneesama particularly tearfully-hard, but eventually takes off with all the others. Tamao and Nagisa are left behind, and they throw some stolen glances at Shizuma and Miyuki on the other end of the room. They notice their peeking and eventually come around, with Miyuki telling Nagisa that her French is still too bad, and that she has to work hard to improve. Which means: Extra tutoring lessons.
Eventually Tamao breaks to Nagisa that she has to leave, too. Nagisa is so freaked and upset about this that I wonder what I've been missing - we'll see about that ... in any case, before Tamao leaves, she ties her ribbon around Nagisa's wrist as a soothing Omajinai, lest she study well and may no harm come to her.
Miyuki and Shizuma tutor a struggling Nagisa. Eventually taking a break, she stumbles across Amane, who she helps finding a bucket she was seeking. The two of them tend to Amane's horse and start talking. Here, we learn that Miyuki obviously has a standing arranged marriage she doesn't seem to be all too fond of. Some more seemingly meaningful talk between them which needs to wait for the sub. Eventually, Amane says something which startles Nagisa so much (and which I can't remember) that it causes Nagisa to topple over fall off the fence she was sitting on. Just when Amane was bending over Nagisa, Shizuma arrives at the scene. *shokku*
Nagisa is highly embarrassed, apologizes and rushes back to the lessons. Shizuma gives Amane a chilling jealous glare, calling her with her nickname "Prince Ootori", very different to the friendly talk they had before several times. Shocked and taken aback, Amane notices that Shizuma clearly misunderstood the scene, but can't correct her impression.
The tutoring ended late at night, and as a reward, Shizuma tells Nagisa that she can have a look at the summer festival. It turns out to be only getting a peek at the fireworks. The two of them alone, Nagisa tells Shizuma that strangely, throughout Summer School she was always feeling a bit sad and lonely, even though she was with the others all the time. I refer to Cuddlyness' translation here - Shizuma's quiet reply "So was I" was initially misunderstood by Nagisa (attributing it to the fireworks), but eventually (unless my memory fails me) the shrieks up when she realizes the real meaning behind Shizuma's words.
Shizuma drags Nagisa poolside in a sweeping dancelike motion. There, she realizes the ribbon around Nagisa's wrist and asks what this might be. Nagisa responds that it's an omajinai with Tamao, and Shizuma's face darkens. In a jealous outburst, Shizuma tries to remove the ribbon, but Nagisa resists, obviously confused by it. Shizuma doesn't let up however, and struggling, the both of them fall into the pool. Here (I've commented enough on the lack of realism before), we have another Nagisa-big-eyed-like-a-deer-in-a-headlight scene, but when Shizuma moves in to really kiss her, her eyes briefly widen in surprise before she closes hers and accepts it. It was initiated by Shizuma, but Nagisa didn't resist. Symbolically, Tamao's already-loosened ribbon slips off Nagisa's wrists completely...
Scene change to Nagisa under a hot shower, still dazed by the experience and pondering what happened. Shizuma walks in to bring her towels, and she leaves a red dress for Nagisa to wear afterwards. Then, it's Shizuma showering, and Nagisa looks around in Shizuma's room, noting that this is the first time for her to ever be here. Returning from the shower, Shizuma dons a fairly aggressive dark dress emphasizing her mighty cleavage further with a little sapphire pendant.
Shizuma wants more and moves in on her again. Nagisa in exchange is still confused and visibly scared, backing away and toppling over the bed while doing so. Shizuma moves in and straddles her, capturing Nagisa by her wrists. Wide-eyed Nagisa watches the forceful Shizuma, but she doesn't scream or increase her efforts to break free, rather she gradually retreats into her known half-conscious "I can't move" mode. Then. Shizuma starts to fondle Nagisa, who reacts to it but doesn't resist anymore. We see Shizuma start unpacking the goods, but when she moves in to kiss them, whispering Nagisa's name, a memory of a still-unknown blackhaired Girl hits her, and she freezes in midmotion with a painful look on her face, sweatdrops falling.
Nagisa realizes that something is wrong, seems to "come to" again, sees Shizuma in this scary state and breaks free. Thanking Shizuma for the great day, she quickly makes her getaway, while Shizuma remains hunched over, obviously tormented by memories, barely noticing Nagisa's retreat. Rushing back to her own room still in Shizuma's red dress, she's noticed by the passing Miyuki, who draws the right conclusion. "Shizuma!"
Tamao returns with literally a mountain of gifts, only to find a dejected Nagisa near tears. She's still totally shaken from the incident and barely manages to speak coherently. Tamao notices that her ribbon is gone, to which Nagisa apologizes in a dazed-desperate state over and over again. She doesn't know where she lost it. She's so sorry. She just doesn't know.... and gently, Tamao moves in to hold her comfortingly while Nagisa continues to weep.
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Great, great episode. Here, we see both the gentle and yet also the jealous-possessive side of Shizuma, who always stayed the most interesting and complex character throughout the show IMHO. It will be interesting how Nagisa will react to the relevation, because it should be obvious even to her 1) what kind of interest Shizuma has toward her and 2) that something is terribly amiss with our Etoile. Just like she slowly comes to realize that Shizuma is special to her aswell.
Tamao is the other kind of friend. Genuinely concerned about Nagisa in a non-possessive way, but this also limits her own interests tremendously.
It will be interesting to see this play out. In any case, SP clearly ramped up the drama quite a bit. Good!