Miyuki Hoshizora is the leader of the Cures in Smile Pretty Cure!. She is a bright, energetic girl who loves fairytales. Although she is a scatterbrain and gets flustered easily, she has the determination to get what she wants and is seldom unhappy. Whenever she is happy, she is fond of saying "Ultra happy!". At the start of the series, she is a newly-transferred student at Nanairogaoka Middle School.
Miyuki's Pretty Cure alter ego is Cure Happy. She controls the power of the Holy light.
In her normal form, Miyuki has dark pink hair with straight bangs, with the back worn in cone-like rolls held with yellow bows. When let down, it is shown to reach just past her shoulders. She has matching dark pink eyes. Her casual outfit consists of a light pink, long sleeved dress with a 2-tiered skirt of light and hot pink ruffles, a pink hoodie with yellow lining, white stockings with pink lining near the top, and pink sports shoes. Her summer outfit consists of a pink ruffled blouse, light blue trousers and dark pink high-heeled sandals. She wears her school uniform with a pink tie, and is the only one out of the five girls not to accessorize her uniform with a sweater.
As Cure Happy, Miyuki's hair becomes bright pink, and her hairstyle changes to long pigtails with loose strands at the top of her head. Her eyes also become a brighter shade of pink. Her tiara has two angel wings attached at the sides, and she wears it in the center of her head. Her outfit is mainly light pink, with dark pink lining and white highlights. Her sleeves are double-layered with a frilly piece below, and the bow at her chest is big with a small frilly piece behind it. Her back of her top is split into two coat-tails, and her skirt has a frilly layer underneath it. Her arm protectors are short with hot pink ribbons on the wrists. Her boots are knee-length, with light pink folds at the top and small hot pink ribbons.
In Tiara mode, her white tiara is replaced by a golden crown worn in the center of her head. The centerpiece of her tiara is a pink heart, and the two angel wings at the sides of her tiara turn golden as well. Her white angel wing earrings are replaced by gold ribbon-shaped earrings with pink hearts in the center.
In her Princess form, Cure Happy has a light pink gown over her normal superhero form with a multi coloured bow in the middle. Her hair is bigger and longer with the same golden tiara and angel wings at the side as the tiara mode.
Miyuki is a bright and energetic girl who loves fairytales. She is always happy and optimistic, making her seem very naive. Simple things such as eating cake can make her happy, and she is fond of using the phrase "Ultra happy!" to show her joy. In contrast, when things do not go her way, she shows her disappointment by saying "Ha~ppu~ppu".
She is also extremely unreserved, openly asking Akane and Yayoi to become Pretty Cure with her, and hugging and jumping on Akane/Cure Sunny despite knowing her for only a day. She often openly proclaims her love for her friends, announcing that she really likes Reika in Episode 5 and Candy in Episode 6.
Miyuki likes to play-pretend and was thus extremely excited to become a Pretty Cure, proclaiming her Cure costume as "cute" and that being a Cure is like "being a superhero on TV". Despite this, she has little confidence in her own powers as Pretty Cure at first, calling the Akanbe monsters "frightening" and preferring to run away instead of fight. However, she gains confidence in her abilities over time, and though she does not come off as a very reliable leader, her enthusiasm often helps her to lead the other Cures in battle.
Miyuki often gets overexcited over small things and ends up hurting herself in the process. In one instance, she got so excited when she learnt that there were 5 Cures in total that she fell backwards and hit her head. Another time, she was so amazed at all the fairytales in the Magical Library that she tripped over a book and fell flat on her face. She is shown to be bad at sports, prone to catching balls with her face and falling flat on the ground. A running gag in the series is how Miyuki always gets hit in the face by random objects. Thus far, she has been hit by Candy, a volleyball, a soccer ball, Pop's storybook and the "turning ti~ny" mallet. This clumsiness extends to her Cure form as well, when she failed to aim her finishing attack at an Akanbe and hence missed it totally.
As she loves fairytales, Miyuki's favorite pastime is reading storybooks. During her self-introduction in class, she explained that she loves reading fairytales because the happy endings always leave a warm and happy feeling inside her heart, which she summarizes as a feeling of being "ultra happy!". The most important thing to Miyuki is to be happy and to smile. She hates seeing others cry and does her best to cheer them up. In Episode 2, despite being defeated by an Akanbe, she insisted on smiling, saying that she won't cry or "happiness will be gone".
Due to her love of reading, she seems to know most of her fairytales well. The first time she faced up against Wolfrun, she hid behind a brick wall, naively telling him that à la The Three Little Pigs story, he would not be able to get her. However, her strategy failed when Wolfrun created an Akanbe out of the brick house.
- Happy Shower - Cure Happy charges her Smile Pact with enough spirit to make it glow and grants her power to preform her attack. When this is done, the Smile Pact disintegrates into pink energy. Cure Happy uses the energy to create a big heart with her hands and the heart reduces its size to fit in her fingers, that are shaped into a heart too. Then, she releases the attack towards her enemies.
- Cinderella Happy Shower- A larger version of Happy Shower, used when in solitary Princess Form in episode 39.
- Happy Shower Shining - An upgraded version of Happy Shower.
- In her introductory speech, Cure Happy says "kirakira", which, like "pikapika" (said by Cure Peace), is the onomatopoeia equivalent of "sparkle" in Japanese.
- Miyuki is the only Smile! Cure whose real name does not contain a color name in it.
- The name "Hoshizora" means starry sky. Meaningly she is the only leader that has no resemble in her Cure name.
- Cure Happy is the second Cure to represent happiness, after Cure Passion. She is also the second to have a catchphrase involving happiness, after Cure Peach.
- Miyuki is the second lead Cure to start out as a new girl at her school, after Tsubomi from Heartcatch Pretty Cure!. Other Cures or Cure-like characters that got their "new kid at school" moment were Hikari, Mai, Michiru and Kaoru, Urara, Kurumi, Setsuna and Ellen.
- Cure Happy is the second Cure to have pink pigtails after Cure Melody of Suite Pretty Cure. She is the third leader to have pigtails overall after Cure Peach and Cure Melody .
- She is the fifth Cure to have pink hair, following Cure Dream from Yes! Pretty Cure 5 and Yes! Pretty Cure 5 GoGo!, Cure Passion (transformed only) from Fresh Pretty Cure!, Cure Blossom from Heartcatch Pretty Cure! and Cure Melody (transformed only) from Suite Pretty Cure♪.
- Miyuki is the third leader to have yellow hair accessories with pink hair, after Nozomi and Tsubomi.
- Cure Happy is the fourth lead Cure with no midriff-baring costume, following Cure Bloom/Bright, Cure Peach and Cure Blossom.
- Miyuki is the second cure to first meet mascots by them falling on her head. the first being Tsubomi.
- Miyuki is voiced by Fukuen Misato, who voiced Mijumaru (Oshawott in English Version) in Pocket Monsters: Best Wishes. Coincidentally, she is paired with Candy, who is voiced by Ōtani Ikue, who voiced Pikachu as well.
- When she is surprised or happy/excited her pigtails go up, when she is sad/depressed or relieved they go down.
- She seems to be the only Cure in Smile Pretty Cure that doesn't use her portions of her power in combat, as she seems to only ever use Happy Shower.
- In the Smile! Pretty Cure Movie her third special form appears, Ultra Cure Happy. Others are Tiara Mode and Princess Form. That means she is first Pretty Cure who has three Special forms in her own Season, without counting Pretty Cure All Stars New Stage or Pretty Cure All Stars DX- Movies.
- Cure Happy is the first Cure to transform into a giant robot.
- Miyuki is the second lead Cure who was sucked into the fairy tale of Cinderella and became Cinderella, after Nozomi Yumehara.
- Miyuki is the second Cure to switch bodies with a Pretty Cure mascot (Candy), after Cure Pine (who switched with Tarte).
- Cure Happy is the only Smile Cure who transforms into her Princess Form alone.
- Cure Happy is the only Cure to not perform a dual attack with another Cure. Her comrades do that in Episode 47.
- In Episode 13, Miyuki reveals that she has a crush on the legendary fairy tale hero, Peter Pan.
- A magical girl similar to Cure Happy made various cameo appearances on Outbreak Company anime series.
- Like her counterpart from Yes! Pretty Cure 5, Nozomi Yumehara, Miyuki lacks athletic skills.
- Miyuki appears as Cure Happy at the beginning of the fifth episode of Happiness Charge Pretty Cure!.
Her name is similar to Miyuki Takara from Lucky Star.