Kanade Sakurai has a crush on Yukino, her fraternal twin sister. Yukino appears to be well aware of the fact, but seems to play it off for laughs — although she likes to tease Kanade a bit too much for comfort. Then, there is Sakuya Kamiyama, an underclassman of the two, who harbors a crush on Kanade herself. Stuff happens to them.Candy Boy started off as a gimmick one shot ONA but the notion proved so popular that more episodes have been produced. This caused some confusion with episode numbering: the first episode (the original ONA) is usually not counted, with the technically second one designated as "episode 01", etc. For simplicity's sake, think of the original ONA as "episode 00". Still, there is also a prequel, called "EX01" — and then there are the various music videos, made from scenes of the original series. Sadly the show couldn't last and ended after the DVD special (EX02). However, the story has continued in a manga, though it's more of an Alternate Continuity.
Alternate Continuity: The manga, in which Kanade and Shizuku's relation is significantly more positive than in the anime. Moreover, the manga introduces several new characters: Yurippe, Isako, Masumi, and Eri, who does not appear in the anime.
Animated Music Video: The first episode was originally a prolonged video for the song "Candy Boy" by Meilin.
Annoying Younger Sibling: Shizuku Sakurai appears this way but there is a reason behind her "annoying" behavior that makes her more sympathetic.
Deadpan Snarker: Kanade — most of the time, probably in an attempt to keep her cool in front of Yukino.
The Ditz: Subverted with Yukino, as while she appears like that at first (since she tends to enjoy life as it comes without sweating the "little details"), she's actually the most level-headed of the four characters.
Erotic Eating: Fingers. There was cake. Plus the rice-off-the-mouth kiss in episode 7.
Fangirl: Sakuya is Kanade's In-Universe personal fangirl... not that the latter is particularly happy about it.
Fanservice: Surprisingly averted, given the show's content. Even the swimming pool episode is rather subdued, much to Sakuya's dismay.
Hotter and Sexier: The manga, which has some actual Fanservice and adds sexual tension between Kanade and Yukino (mainly on Kanade's side). This makes sense, considering that the artist, Hiro Touge, primarily works on either ecchi or straight-up hentai titles.
Improbably Female Cast: No male characters in sight of any relative importance, though a few can be seen at the train station.
Odd Couple: Despite being sisters, Yukino and Kanade have quite different personalities. For one, Kanade is much more serious and often gets irritated by her sister's ditziness, so it's amazing they get along so well.
Romantic Two-Girl Friendship: For all the yuri vibe the makers obviously strive for, the relationship between Kanade en Yukino still comes closest to this kind—although it's nevertheless a bit unusual among sisters.
Also Kanade. Yukino calls her out on it in EX02 where it's revealed Kanade came to watch Yukino swim five times in one week.
Suspiciously Specific Denial: As well as humorous, the note on Kanade and Yukino's door, if read by a passerby, would seem rather suspicious. Subverted since they really aren't shown doing anything explicit in their room.
Note on the door: Seriously, why won't anyone knock on the door? Really. It's not that we're doing anything suspicious, but it's common sense to knock on the door. Yes, we may be a damn shameless couple, but we aren't doing anything! There isn't much else I want to say about this, but let me say it again: KNOCK DAMNIT!!
Sweet Tooth: Yukino loves sweets... and gets constantly scolded by Kanade.
Tomboy and Girly Girl: Kanade is more tomboyish and Yukino more the girly one, though it's in mannerisms rather than appearance.
Shizuku depending on how you view her. She does have a tsuntsun side towards everyone except for Yukino, the sole recipient of her deredere side. However while unclear, it is hinted at that Shizuku likes Kanade and acts tsuntsun towards Kanade out of jealousy.