Yuna's New Sibling Part 1 is the nineteenth episode and part one of the fifth season finale of Yuna's Princess Adventure.
Prince Hiro and Princess Luna are expecting a newborn foal and Princess Yuna, Princess Snowdrop and Princess Solarna are excited about being big sisters, Then, There was a Prophecy that a newborn foal of it's royal blood that will be the heart of the balance of Good and Evil and Aku and Tirek wanted to destroy the Prophecy and the Journals, Now it's up to Princess Yuna, Snowdrop, Prince Jeremiah, Sunrise Shimmer, Prince Sunlight, Princess Lilly Sparkle Rose, Princess Twila, Princess Flurry Heart, Princess Skyla, Armor Bride, Sweetie Heart, Scander, Britney Sweet, Golden Apple, Arachna, Dragonsly, Brownie, Red Beret, Emerald, Thunder Spectrum, Blue Star, Sunbeam, Willow Apple, Apple Feather, Game Player and Game Facer, Quaker, Treasurer, Round Up, Hurricane Cloud, Indigo Marble, Pound Cake and Pumpkin Cake, Orange Cake, Cream Puff, Zeñorita Cebra, Golden Scissor and Bronze Bracelet, Lucky Horseshoe and Lucky Penny, Birthday Bash, Midnight Sapphire, Stary, Rainbow Chakra, Prince Edmond, Josephine, Judy, Roger, Eliza, Daffodil, Joshua and Katrina, Angus and Fergus, Orlean, Polly, Cullen, Adam Marie, Matilda and their close friends and guardians to stop Aku, Tai Lung, Junjie and Fenghuang. Trouble is that Yuna couldn't stop thinking about the newborn foal.
Dusty the best Prince and racing plane ever!Edit
One day, Prince Dusty Crophopper was racing with Princes Yuna and the other Planes and Dusty won, Everyone and Everypony looked up to him as the best Prince and Racing Plane of all in Equestria.
Racing Practice/Dusty's gearbox overheated/That night/FIRE!Edit
That afternoon, Dusty was on his Racing Practice with Airazor and EVE, Suddenly, Dusty's gearbox was starting to overheat, So he decided to take a brake until it cools off, Later, That night, Dusty was in for a surprise by Yuna, That Prince Hiro and Princess Luna are about to have a baby foal, Suddenly, There's a fire at Sugarcube Corner, Dusty's gearbox as cooled off and ready to put out that fire with Blade Ranger, Lil' Dipper, Windlifter, Cabbie and the Smokejumpers by his sides.
Aku and Tirek returnsEdit
Meanwhile, Aku and Tirek were waiting for very long time to break free from his prison cell, When Thaddeus E. Klang, Feathers McGraw, Tai Lung, Junjie and Fenghuang came, Feathers used his sleeping dart to put Cerberus to sleep and Tai Lung and Fenghuang break the cell and free Aku and Tirek as they're going about planning for revenge against Samurai Jack and his friends, Find the Journals and rule the universe and the next, Unknowing Nimbly spied on them and left to warn the others.
Hiro and Luna's story of AkuEdit
Back at Canterlot, Princess Yuna looked around the Throne Room and saw the glass that shows Princess Sunset Shimmer and the Redeemed Maleficent defeated Aku and send him to Tartarus, Yuna asked her parents, Prince Hiro and Princess Luna about Aku and they explained everything about him.
Luna's Baby ShowerEdit
Later that day, A Baby Shower was celebrated in honor of the arrival of Prince Hiro and Princess Luna's newborn foal Yuna and Snowdrop were excited to become big sisters.
During the party, Nimbly and warned Princess Yuna and her family and friends as Shifu and Ford Pines explains about the Prophecy that Aku and Tirek wanted to destroy. Meanwhile, Aku and Tirek made their plan for revenge against Samurai Jack and his friends by destroying the prophecy and the Journals they don't want it fulfilled as they gathered Queen Chrysalis, The Nightmare Family and Bill Cipher. Back with Yuna and her friends, Yuna was starting to think about being a big sister soon.
Journey to ManehattanEdit
So, Yuna, her friends, their guardians and Dusty arrived at Manehattan as they meet up with Blade Ranger, Lil' Dipper, Windlifter, Cabbie, the Smokejumpers, Maru and Samurai Jack to make sure the prophecy comes true and Stop the Nightmare Family, Bill Cipher, Aku, Tirek and their followers.
Giving Dusty pontoonsEdit
Later, Dottie and Maru gave Dusty his pontoons to be ready for this dangerous mission to stop the Nightmare Family, Bill Cipher, Aku, Tirek and their followers and fulfill the prophecy.
Later that night/Yuna spoke with TigatronEdit
Later that night, Dusty wanted to show Yuna and her friends everything about how he became a firefighter after Yuna learned from him. Snowdrop learned that Blade Ranger is a TV Star, Blade Ranger explained to her that it was a long time ago when his partner Nick Loopin' Lopez died. As Yuna's friends went to bed, Yuna spoke to Tigatron if she'd be a great big sister to the new baby since Solarna is to her.
Luna's in laborEdit
At Canterlot, Princess Twilight Sparkle, King Stephen, Queen Sunset Shimmer, Princess Trixie and their friends were helping Prince Hiro, Princess Celestia, Shining Armor and Princess Cadance watched over Princess Luna when Scorpan and Star Swirl the Bearded arrived and warned them that The Nightmare Family, Bill Cipher, Aku, Tirek and their followers are on their way and they've come to help protect Luna, Suddenly, Luna's contraction has started and she's going into Labor.
- This episode is a mixture of Planes: Fire & Rescue and Twilight's Kingdom Part 1 and 2.
- The episode continues in Yuna's New Sibling Part 2.
- Music score - Planes: Fire & Rescue Main Tites (from Planes: Fire & Rescue)
- Music score - Propwash (from Planes: Fire & Rescue)
- Music score - Out of Production (from Planes: Fire & Rescue)
- You'll Play Your Part -
- Music score - Fire! (from Planes: Fire & Rescue)
- Music score -
- In The Dark Of The Night (Song) - Aku
- Music score - An All New Mayday (from Planes: Fire & Rescue)
- Music score - Sad Mayday (from Planes: Fire & Rescue)
- Still I Fly -
- Music score - Pontoons (from Planes: Fire & Rescue)