Super Mario Issun-bōshi

Super Mario Issun-bōshi (or "スーパーマリオのいっすんぼうし" in Japan) is the second OVA in the Amada Anime Series: Super Mario Bros., released only in Japan. It is based on the Japanese fairy tale Issun-bōshi, "The One-Inch Boy".

Plot
In this fairy tale, a shooting star gives a couple the child they had wished for, Mario, but he is only an inch tall. As the child grows older, he becomes adventurous and after climbing a tree and catching a glimpse of a city past the mountains, he becomes determined to travel there. Concerned for his safety, his Mama and Papa say "no" at first, but eventually Papa realizes that it would be doing more harm to keep Mario sheltered forever. He fashions Mario a tiny sword out of a sewing needle, turns a bowl into a boat with small rocket engines, and makes an oar out of a chopstick for Mario to steer it with. He then brings the boat to the river and bids his son farewell as Mario sets sail, singing as he goes.

Mario sees a Spiny Cheep-Cheep jumping out if the water, a flock of Para-Beetles, and even a Blooper Nanny flying with its brood. At one point, a Dry Bones rises under Mario, but he uses the rockets to fly his boat off its back and get back onto the water, taking a detour through its eye socket along the way, before it clatters apart and sinks back under the river. Later, Mario is caught in a storm caused by a Lakitu, who laughs as her cloud sends rain and lightning down upon him, struggling against the choppy water until a particularly large wave finally sinks his boat.

When Mario opens his eyes, he finds himself in a tiny bed on a bench in the city, with Princess Peach watching over him. She introduces herself and explains that she had been taking a walk after the storm when she spotted him washed up on shore, unconscious, having floated down the river all the way to the city. He thanks her or saving him and tells her that he had come to the city to learn new things, and having grown fond of the cute, tiny Mario, Peach tells him that he should stay there with her, which Mario is happy to hear.

From then on, the two are always together, with Mario riding on Peach's shoulder as she walks around town. But when she hears heavy, crashing footsteps, Peach screams and tries to flee, only to find herself face-to-face with King Koopa. He is in love with her and demands an answer to his (latest) proposal, but she tells him that she would never marry someone like him. Turning red with anger, Koopa prepares to use force to get what he wanted, but Mario jumps off Peach's shoulder and brandishes his sword at the villain. Koopa laughs at the tiny boy's challenge and tries to step on him, but Mario nimbly dodges every stomp. Despite Mario's best efforts, Koopa soon manages to snatch him up with his claws and swallows him whole, as Peach watches in horror. Koopa then returns to harassing Peach, but just as he announces his intent to kidnap her, he is brought up short by intense belly pains cased by Mario jumping around his stomach and stabbing him from the inside out with his sword. Peach realizes what's happening as Koopa collapses at her feet and coughs up Mario. He regains consciousness with Mario still perched on his face, but Mario quickly cuts off his horns and eyebrows with three strokes of his sword, causing the Koopa to run away in humiliation while the humans laugh. Peach thanks Mario for defeating Koopa, and then notices a magic wish-granting hammer he had dropped as he fled, which she uses to grant Mario's wish to become a full-sized young man. The two then get into a hovercraft and fly back to Mario's home to continue their lives together.