Venus Capriccio

Venus Capriccio is a 2006 Shojo manga series by Mai Nishikata.

Second year high school student Takami Habara and third year middle school student Akira Sasaki are childhood friends, having met through piano lessons. However, they are complete opposites: Takami may have the height and looks of a model, but she's really a rough Tomboy, having grown up in a family with four older brothers, and has trouble with dating guys because they are not attracted to her unruly personality. Akira is a guy, but his beautiful Bishounen features could fool anyone and he would rather either play the piano or spend time with Takami than to do other things.

Because of Akira's feminine physical appearance, Takami has always thought of Akira as a "sisterly" figure and her ideal of a girl's image rather than seeing him as a guy, but when Akira spontaneously kisses Takami and confesses his feelings to her, Takami must seriously come to terms that Akira is a guy and what her feelings for him are.

This series contains the following tropes:

 * Almost Kiss: Between Takami and Akira in Chapter 16.
 * Always Someone Better: Akira's reaction to Shinobu.
 * Amusement Park: Chapter 5, along with a Ferris Wheel Date Moment.
 * The Atoner:
 * Attractive Bent Gender:
 * Takami, while disguising herself as a boy to be Mina's "prince" for the PriCon. When Mina dumps her after Mori asks her to be his prince, Akira steps in to be Takami's "princess" and he makes an attractive cross-dressing girl as well. One can wonder why Takami could have just been the "princess" and Akira the "prince," but the reason is fairly obvious.
 * Takami's brothers get Daiki (Takami's third older brother) and Shinobu to cross-dress. Hilarity ensues.
 * Because You Were Nice to Me:
 * Both Takami and Akira learned that playing the piano could be fun from each other.
 * Julian quickly gets attached to Takami because she was the only one nice to help him when he lost his passport.
 * Berserk Button:
 * Akira's buttons get pushed over to things--if anyone so much as harms or gets close to Takami, and just Shinobu being Shinobu in general.
 * In return, Takami's buttons get pushed if anyone either insults or brings harm to Akira in any way.
 * Beware the Nice Ones: Akira really is a nice guy. Just don't hurt Takami.
 * Big Eater: Takami.
 * Bishounen: Akira.
 * Bridal Carry: When Akira shows Takami around Club Blue, he picks her up and calls her his "fiancee," to Takami's flustered confusion. She quickly realizes that this is Akira's own way of showing Takami that everyone was complimenting her on her beauty, not him. He carries her again to her room after she gets drunk by accidentally mistaking Shinobu's beer for ginger ale.
 * But Not Too Foreign: Akira is half-Austrian and half-Japanese.
 * Clingy Jealous Girl: Sayuki.
 * Did You Think I Can't Feel: Akira finally calls Takami out on always seeing him as a "brother" figure instead of as a guy after she imposes on him and stays at his house after having a fight with one of her brothers and she goes so far as to say how much of a better "brother"/"sister" Akira would be compared to her siblings--not realizing that her actions are hurtful to Akira.
 * Dude She's Like in A Coma: Akira tries to kiss a drunken Takami in her sleep, but can't bring himself to.
 * The Glomp: Julian is fond of doing this to Takami.
 * Green Eyed Monster: Akira does not like it when Takami and Shinobu are getting along.
 * Hair of Gold: Akira.
 * Hidden Depths: Kei seems to be a bit of a bully towards Akira, but it turns out he used to take piano lessons too when Takami, Akira, and he were children and Takami realizes that the reason why Kei bugs Akira a lot is really because he wanted to be friends with him.
 * Hot Teacher: Oda Shinobu, Akira's private school teacher during elementary school and Takami's and his new piano teacher.
 * In Series Nickname: Shinobu is fond of calling Takami and Akira "princesses," especially Akira just to piss him off.
 * Kick the Dog: The first time Akira's father ever met Akira, he called his piano playing, "Disappointing."
 * Les Yay: Mina, a girl who got dumped by Mori like Takami did, wants to win the PriCon (Princess and Prince Contest) for the festival to prove to Mori that she can win it (as the reason why he dumped her is because he didn't she could) and asks Takami to be her "prince."
 * Like Sister And Sister: Because of Akira's feminine looks, Takami has always thought of him as an adorable sister and her "ideal image of a girl."
 * Looking for Love In All The Wrong Places: Akira suggests that the reason why Takami has horrible dating records is because she doesn't have the insight to choose the right guys. This happens to be Mina's problem when it comes to guys as well.
 * Masculine Girl Feminine Boy: Akira and Takami.
 * My Beloved Smother: Akira's late mother used to be strict and would constantly make Akira practice the piano all the time so that he could surpass his father, who was a great pianist. It's to the extent where his mother would only place his first place trophies out to be recognized, while any trophies that he received that were lower than first place weren't.
 * No Sense of Personal Space: Shinobu sure likes getting into Akira's and Takami's personal bubbles.
 * Omake: The series' okames kind of reverse Takami's and Akira's roles and make Takami the calm and cool character with Akira awkwardly pining for her.
 * Opposites Attract
 * Parental Abandonment: Akira's father left Akira and his mother, who died in a car accident a few years ago.
 * Plucky Girl: Takami.
 * Red Oni Blue Oni: Takami and Akira.
 * She Cleans Up Nicely: Takami, when she goes to watch Akira's peformance at Club Blue.
 * The Rival:
 * This is how Akira perceives Shinobu as, both as a fellow pianist and for Takami's affection. Interestingly enough, Shinobu knows this and often uses Takami as a way to get Akira to do things for him.
 * Julian, as Akira's father's pupil, becomes one for Akira.
 * Shojo
 * Slice of Life
 * Stalker With a Crush: Following the PriCon, Akira gets extremely popular to the extent that girls are jealous that Takami won't "share" Akira with anyone else and one of them even tries to cut a lock of Akira's hair.
 * Sweet Tooth: Takami really likes cake.
 * Tall Dark and Bishoujo: Takami is this in everything but personality.
 * Tiny Guy Huge Girl: Takami is three centimeters taller than Akita, justified as Takami is older than Akira.
 * Tomboy: Takami, having grown up in a family with four older brothers. Naturally, this is why her mother signed Takami up for piano lessons, and she'll always get overly excited whenever Takami needs to dress up femininely.
 * Yamato Nadeshiko: Or rather, this is Julian's opinion of Takami.