Kashimashi is about a guy, Hazumu, who gets turned into a girl by aliens (he was kind of girly already, but they completely changed him into a girl). Before that happens, he confesses his feelings to his crush, Yasuna (she's the one with the long dark hair), but she turns him down. We find out that it's pretty much because of his gender, although much later on (in chapter 7, actually) we find out that she's slowly been developing feelings for him even though he's a guy--Yasuna doesn't "see" any guys when she looks at the world, just females, but she's gradually started to see Hazumu.
When Hazumu first gets turned down, he decides to give up on Yasuna, but then, (coincidentally or not) after the transformation happens, Yasuna starts seeking her out and acting interested. However, added to the mix are three other love interests (using the term loosely here for the first "person"): the alien's ship, turned into human form (the alien and his ship have come to stay with Hazumu... -_-), who addresses Hazumu as "Onenii-sama" (big sister+brother) and is all clingy, and two of Hazumu's friends, one male and one female. I'll skip over the guy cause he's not really relevant here. The female friend, Tomari, has always been protective of Hazumu, and (iirc) has gradually developed feelings for him. She gets upset when Yasuna turns him down and then suddenly acts interested. Oh, and Hazumu is basically confused about what she feels, although she thinks it's impossible for her to be with a girl now that she's a girl.
Okazu has a better summary, if you want more info.
Kashimashi has been licensed by Seven Seas.
p34:
After turning down Hazumu, Yasuna says to herself, "If you [Hazumu] were a girl, then..." Little does she know that's exactly what's about to happen. ^^
p54:
Yasuna and Hazumu's eyes meet, but neither says anything.
p58-64:
Hazumu finds a note in her desk from Yasuna, asking her to come to the music room after school.
When Hazumu shows up, Yasuna says she didn't think Hazumu would come. Yasuna apologizes for before (when she rejected Hazumu, at the beginning of the manga), and Hazumu says it doesn't bother her anymore. Yasuna says she wants her rejection to bother Hazumu, because the truth is that she really is in love with her...
Hazumu is surprised, and says she doesn't understand. She says, "But I'm a girl now..."
p80-93:
Tomari is taking Hazumu shopping for lingerie, when they run into Yasuna. Hazumu gets flustered and doesn't know what to say; she remembers Yasuna's declaration of love.
In the lingerie shop, Tomari yells at Hazumu, saying girls can't be topless in public like guys can. Hazumu asks Tomari to pick out bras for her, but Tomari says she should just choose what she likes. Just then, Yasuna shows up again, saying she's picked out some bras she think might look good on Hazumu. She helps her put one on. She says it looks cute on her and asks her how it feels. She says it's kind of embarrassing, even though she didn't mind being naked before. Yasuna tells her that's what it's like to be a girl. She tells her that she will be able to keep on getting cuter now that she is a girl.
Just then, Tomari bursts into the dressing room with a bra for Hazumu. Yasuna thinks it's not girly enough, and they argue. Hazumu has finally had enough and yells at them to cut it out.
As Hazumu is paying for her purchase, Tomari tells Yasuna that since she dumped Hazumu, she should leave her alone so she (Hazumu) can forget about her (Yasuna).
Tomari asks Hazumu if she's doing all right with the whole Yasuna thing. Hazumu says that she is, because when she confessed to Yasuna she hoped that they could remain friends even if Yasuna turned her down, and they have. She continues on to say that things wouldn't work between them now because she's a girl--she doesn't think two girls can be lovers. She thinks to herself that she doesn't understand why Yasuna said the things she did now that her body has changed and it isn't possible for them to be together.
p100-101:
Tomari freaks out because Hazumu is changing in the girls' changing room. A character whose name I don't remember says that Hazumu is changing in the girls' room because she is a girl. When Tomari protests that Hazumu was originally a guy, Hazumu offers to go to the guy's changing room, but Tomari says that's even worse. Some of the other girls join the discussion, saying nobody minds having Hazumu there because it's Hazumu-- if it was anyone else they'd kick him out. Someone asks Tomari if it bothers her, to which she emphatically replies that it doesn't. The other girls keep on talking about it, saying that Hazumu is cute and that it feels like Hazumu has been a girl from the beginning.
p108-110:
The spaceship girl hugs Hazumu, and when Tomari asks who she is Hazumu tells her she's one of the aliens staying at Hazumu's house. Incindentally, the spaceship girl calls Hazumu "Onenii-sama," which is a combination of the word for brother ("Onii-sama") and sister ("Onee-sama"). The spaceship girl tells Tomari that she and Hazumu sleep together every night and that they took a bath together the day before. Tomari freaks out, but Hazumu tells her it's okay because they're both girls. The spaceship girl wants Hazumu to hurry home, since her mother has bought her lots of girly clothes (Hazumu's mother is really into dressing Hazumu up like a girl, especially now that Hazumu is a biological female), including bras. She also bought matching pajamas for Hazumu and the spaceship girl.
Tomari leaves, thinking that she doesn't like the spaceship girl.
p114-118:
Tomari protects Hazumu from reporters. Tomari thinks to herself that things are the same as always, that the old Hazumu is still there even though her form has changed. Hazumu apologizes to Tomari for having Tomari protect her, and Tomari says that it's all right. Tomari says that she thinks of Hazumu as a younger sibling (she says "brother" at first, then corrects herself, saying "sister"), though it seems that might not really be the case...
p130-137:
Yasuna comes to see Hazumu in the garden (Hazumu is part of the botany club). They talk a bit about the garden, and Yasuna says that she remembers that Hazumu brought her a plant once.
Yasuna points out where the music room is--the window is visible from the garden. She says that while she's in rehearsal, she can see the garden well, and that she's been watching the plants grow and change color as the seasons change. She says that Hazumu has the power to make the world beautiful. Then Hazumu says that she's heard Yasuna playing flute. Yasuna leans in to kiss Hazumu.
Just then, Hazumu's best friend comes in. Hazumu, embarrassed by what just happened with Yasuna, hurries off with him. When Hazumu gets back to the classroom, Tomari asks her what's wrong, and tells her she should go home if she's not feeling well. Hazumu says she's fine.
p142-147:
Looking at a picture she's drawn of Hazumu, Yasuna says that she's always on her mind.
One of the aliens asks Hazumu which girl she's going to choose, Yasuna or Tomari. Hazumu freaks out. The spaceship girl interjects that Hazumu is going to be with her, because Hazumu was her first kiss (she's talking about the time when she hit Hazumu while in spaceship form). The alien guy says that from his observations, Hazumu seems to be interested in both Tomari and Yasuna. Hazumu protests that they're just her friends, and that she's a girl now. The alien guy asks if there's some sort of regulation against same-sex love on Earth, and Hazumu doesn't seem to know what to say in return.
p159-160:
Hazumu says that her heart pounds when she's around Yasuna, but she doesn't know if what she's feeling is (romantic/sexual) love. The alien guy, who's now posing at a teacher at Hazumu's school, comments to her that Yasuna doesn't see guys, or if she does that she only sees them as things (literally, "inorganic material").
p163-164:
Hazumu is looking at a picture Yasuna drew a while back, back when Hazumu was a guy. She recognizes her old self in the drawing and sees that she's been drawn in more fully than any of the other guys in the picture. She remembers the alien guy's words about Yasuna not seeing men, and wonders what the drawing signifies.
Detailed description of chapter 7:
Hazumu sees a drawing Yasuna did a year ago, that has him in it despite the fact that she didn't draw in any of the other guys in the scene.
We find out that the aliens are researching "love" because their race is going to die out--they're very highly evolved, and developed some crazy dangerous technology, and in order to not use it they stopped feeling emotions.
Hazumu's class goes on an art field trip. Hazumu hangs out with Yasuna and Tomari, who both seem more interested in drawing her than the scenery.
They return to the school, and Tomari asks Hazumu if she still has feelings for Yasuna. Hazumu is surprised by Tomari's question, and Tomari quickly tells her it was nothing, then apologizes for asking something weird and runs off. Yasuna comes up to Hazumu afterwards, but she didn't hear Tomari and Hazumu's exchange. Hazumu confesses to her that she saw a picture Yasuna drew the year before, one that had her (in guy form) drawn in. As she first brings it up, they trip and fall; this is the second time Hazumu has fallen on Yasuna, the first time happened at the very beginning of the manga, back when Hazumu was a guy. Anyway, Yasuna confesses that she's never been able to properly see men's faces. Hazumu was the first guy that she became conscious of. She then tells her that she was happy when Hazumu confessed to her, but couldn't tell her (him, then) that she felt the same way, because she was afraid that she'd stop being able to see him someday. She can't even see her father properly. But when Hazumu became a girl, and she could see her clearly, she realized that she really did care for her terribly. She apologizes for her selfishness and runs off. Hazumu, sitting alone in the classroom, thinks to herself that she knew nothing about Yasuna, knew nothing of Yasuna's suffering and despair. Yasuna enters the classroom.Yasuna says that she doesn't want to have any more regrets. Hazumu thinks to herself that she has to stop Yasuna (I think... the word she uses can have a variety of meanings), because Yasuna has been hurt so badly. Yasuna kisses Hazumu. Tomari walks in on them. And that's it for chapter 7!