Manga / Koi Kaze
Koshiro & Nanoka

After his girlfriend dumps him for someone else, 27 year old Koshiro has a chance encounter in the subway with Nanoka, a 15-year-old high school girl. He later meets her again at the entrance to an amusement park and since he has just been given two free tickets to it, he invites her to go with him. Each being rather depressed over the end of a relationship, they immediately feel some emotional connection across their age difference as the afternoon progresses.

On leaving the park, they suddenly discover that they are brother and sister when they both recognize and greet their father as he's arriving. This comes as quite a shock, since they haven't seen each other since their parents got a divorce with split custody some 10 years ago. Moreover, Nanoka is now moving in with her father and brother since their house is much closer to the high school she's attending. Against their better judgment, the first spark of mutual attraction slowly ignites into something deeper and more powerful as time progresses, especially since Nanoka develops a huge big brother complex and she is not deterred in the least by Koshiro's boorish and unsociable nature.

Koi Kaze started out as a manga series which then got adapted into an anime series in 2004 and immediately received a lot of attention for its harrowingly realistic examination of sibling incest. The painful and guilt-ridden romance between Koshiro and Nanoka is credibly full of angst and Belligerent Sexual Tension as the two struggle against their desires, refreshingly devoid of the blithe disregard for social mores and fanservice most shonen series on similar subjects tend to have.

This series provides examples of:

  • Artists Are Not Architects: Completely subverted by the manga. The manga could only have been drawn by someone who did know how to do technical drawings because it looks like it was drawn in the exact same way that Architects and Engineers used to do design drawings, ink on linen, before any shortcuts were available. It really seems like the artist wanted to show off as many extreme high and low perspective angles as he possibly could given the number that show up in the manga.
  • Arranged Marriage: Koshiro works in an omiai (dating arrangement) office. He even faces the possibility of having one of these dates at some point. He refuses.
  • Adaptation Distillation: The anime is, with a few exceptions, comprised entirely of events from the manga, but it compresses the two-year period encompassed in the manga (three springs) to one year (two springs). Several of the largely standalone storylines were also cut out to account for the much shorter time frame. Also, oddly, the events of the manga's second chapter were made into an unaired episode 8 of the anime, later restored to the DVD release.
    • Pragmatic Adaptation: While the anime took almost all of its major plot points from the source material, they were shuffled around to better fit the anime format - some events from early in the manga happened quite late in the anime, and certain scenes were transposed into happening during different storylines or settings, which leads to those changed events having a different context because of how different the relationship between Koshiro and Nanoka is when they happen.
    • All of the side characters have reduced roles in the anime, due to time constraints, and some side characters and their stories were even cut completely.
  • A Date with Rosie Palms: Koshiro is jarringly and explicitly shown to engage in this on impulse due to his escalating feelings for Nanoka. It serves as a strong point of guilt for him, and he feels very out of control after the fact.
  • Bittersweet Ending: At the end of the anime, Koshiro and Nanoka are together and happy, but there is unmistakable symbolism that, at the very least, they are still facing a very difficult time to come. The makers of the anime obviously wanted to make a point here.
    • The manga has some foreboding symbolism in the chapters leading up to it, but ends on a more positive tone, with Koshiro and Nanoka contemplating the inevitable challenges ahead (symbolized by the park where they "met" on the verge of closing) with open eyes and resolving to stick things out anyway.
  • Bishounen: Somewhat hilariously subverted. It's shown that before meeting her brother for real Nanoka envisioned him idealistically as being kind, helpful, and very much a pretty boy. While the first two eventually are shown to be the case as Koshiro grows closer to her, a pretty boy he is not. Despite Nanoka fostering romantic feelings for him, she even once muses that he doesn't really fit her idea of 'good-looking'.
  • Brother-Sister Incest: Goes without saying. This series also thoroughly deconstructs the usual flippant portrayals of this trope found in other series.
  • Boyfriend Bluff: Makie is shown to have a polite and persistent, but unwanted, suitor. She doesn't have a good way to get rid of him without being very rude. Cue one of these with her making her son pose as her supposed "boyfriend" during one of his visits. Koshiro is at this point old enough for the ruse to work, but clearly uncomfortable with it.
  • Cherry Blossoms: You can't have a Japanese romance without them.
  • Christmas Cake: Koshiro's family and coworkers wonder why a guy his age isn't married yet.
  • Comic-Book Time: Averted; Nanoka clearly grows older as time passes.
    • Koshiro's last words in both the anime and manga, said with an emotional expression that contrasts jarringly with his numbness at the series's beginning: "Love you.... I love you."
  • Series Continuity Error: At one point in the Anime's episode 6, another student offers to carry some boxes in Nanoka's hands, only he sets off in the opposite direction she was headed. In another scene Nanoka is shown having high set pigtails at first but later low set ones.
  • Deliberately Bad Example: Odagiri openly lusts for high-school-aged girls and sure wishes he could be in Koshiro's situation with Nanoka—which, of course, is exactly why he's not; he's mostly there just to remind us Koshiro is nothing like him and never asked for this whole situation to be foisted on him in the first place.
  • Driven to Suicide: Nanoka at one point suggests committing lovers' suicide, but Koshiro objects. It seemed intended not to be taken too seriously, but her reason that it would much easier than trying to figure out their relationship implies she was at least half-serious.
    • Koshiro not replying to that suggestion immediately implies that he was also seriously considering it.
  • Earn Your Happy Ending: What Koshiro and Nanoka are still striving to do by the end.
  • Ferris Wheel Date Moment: In the first episode, before they knew they were siblings.
  • First Kiss: A bit ironic when Nanoka initiates a serious kiss with Koshiro and then she yells, "Aahhh! It's gone! My first kiss!"
  • Gallows Humor: Most of the next-episode previews.
  • Gecko Ending: A mild example, as the anime ended a few months before the final chapters of the manga were released. Despite being over different time scales, the anime and manga actually follow surprisingly similar plot paths towards the end. However, there are a few notable differences - aside from the fact the manga covers more detailed territory by having more events happen, the anime has Koshiro resign from his job whereas in the manga he continues to work there. The anime also ends with Koshiro and Nanoka having another date at the amusement park unaware that it's scheduled to be demolished soon, whereas in the manga they aren't shown to have such a date, but they outright comment upon the park's upcoming closure. The differences in part serve to give the endings slightly different meanings, see the Bittersweet Ending entry.
  • Hard-Drinking Party Girl: Chidori, who once partied so hard that she was calling herself "Midori" as she pressed more booze on Odagiri to get him drunk with her. In addition to drinking hard, however, she's also rather hard-bitten and sometimes gets rather mean when she's drunk.
  • Hidden Heart of Gold: What Nanoka thinks Koshiro has. She's not wrong, at least where she's concerned.
  • Huge Guy, Tiny Girl: Koshiro's a big guy. Tall, heavy set. Nanoka, though almost 18 by the end of the series, is still tiny. He's well over a head taller than her.
    • A bit less pronounced in the manga, since Koshiro is slimmer there.
  • I'm a Man, I Can't Help It: Invoked by Koshiro in a next-episode preview, where he uses this as an excuse for staring at Nanoka's underwear.
  • Invulnerable Knuckles: Averted - In the manga after Koshiro asks Chidori to start dating, she punches him in the face. Two pages later, it is shown that her knuckles are hurt as much as Koshiro's face.
  • Jerk Ass: Koshiro for the most part, until he and Nanoka decide to hell with everyone else, they will be together.
  • Love Bubbles
  • Luminescent Blush: This is more evident in the manga which gives this to almost everyone, but damn you really don't expect to see a bulky guy like Koshiro blush as hard or as often as he does.
  • May–December Romance: Aside from being her brother, Koshiro is also twelve years older than Nanoka is.
  • No Periods, Period: Subverted: Nanoka has her first period in three months and suffers some severe cramps from it.
  • Not Blood Siblings: Averted; though the series offers a few hints here and there that it's going to pull this particular cop-out and tell us Koshiro is actually adopted, it ultimately pulls the rug out from under everyone wishing this were the case.
  • Sexy Discretion Shot: Used a few times, as the series is designed to portray the situation realistically but isn't in it at all for fanservice. Koshiro is in a few scenes heavily implied to be masturbating (one of which he later confirms in a guilt-ridden internal dialogue), and eventually he and Nanoka give in to having sex with each other, but the audience never gets shown anything graphic.
  • Solomon Divorce: Nanoka and Koshiro are apparently only reunited for overall convenience.
  • Surprise Incest: They find out they're related before their first "date" is over, but they've already developed feelings for each other by then, even if they both try to pretend otherwise after the revelation.
  • Take That: If his comments about wishing to have a cute little sister are any indication, Odagiri is this to people who would watch this show in hopes of it having incest Fanservice.
  • The Chikan: Nanoka runs into one once on her way to school. It's not a major plot point, but it occurs shortly after Nanoka got into an argument with Koshiro because she felt he was being annoyingly overprotective of her, and the experience led her to appreciate that Koshiro meant well.
  • Umbrella of Togetherness: Turns up in a couple of episodes, especially during the rainy season.
  • Visible Sigh: Also makes an appearance or two. One humorous variation had a cloud forming over Nanoka's head and exploding with an audible pop when a boy mentioned rumors he'd heard that she had a brother complex.