"Soreike! Anpanman: Mija to Mahō no Lamp" is a feature-length anime film based on the popular "Anpanman" franchise, which centers on the adventures of Anpanman, a superhero made of anpan (a sweet bread filled with red bean paste). The story revolves around Mija, a young girl who discovers a magical lamp in the forest. This lamp, when rubbed, summons a genie named Lampman, who grants wishes to those who possess it. Mija, initially unaware of the lamp's true power, accidentally summons Lampman and makes a wish that sets the plot in motion.

The narrative takes a turn when Baikinman, a recurring antagonist in the series, learns of the lamp's existence and schemes to steal it for his own selfish desires. Baikinman's plan involves using the lamp to gain unlimited power and control over the world, threatening the peace and safety of Anpanman and his friends. As Baikinman's actions escalate, Anpanman, along with his companions such as Shokupanman and Currypanman, must intervene to protect Mija and prevent the lamp from falling into the wrong hands.

Throughout the story, Mija's character undergoes growth as she learns the importance of responsibility and the consequences of her wishes. Her interactions with Lampman and Anpanman highlight themes of friendship, courage, and selflessness. The film balances moments of lighthearted humor with action-packed sequences, as Anpanman and his allies confront Baikinman and his minions in their quest to safeguard the lamp.

The climax of the story involves a decisive battle between Anpanman and Baikinman, with the fate of the magical lamp hanging in the balance. The resolution emphasizes the values of teamwork and the power of good over evil, staying true to the core themes of the "Anpanman" series. The film concludes with Mija gaining a deeper understanding of the lamp's significance and the importance of using its power wisely, leaving a lasting impression on both the characters and the audience.