一位名叫农乃香（野村周平饰演）的普通高中生，由于父母离婚，搬进了图画书作家、叔叔农乃有太的空房子，开始了自己的生活。向偷偷地爱上了他的同学美乃奈，但美乃奈偷偷地向向的好朋友方志章倾诉。
由于无力支付生活费用，她的继母把索菲和她的两个姐妹送到一家帽子店当学徒。两姐妹很快离开了帽子店，去追求各自的梦想，但只有索菲坚持了下来。一天，一座机动堡垒来到了小镇旁边。传说堡垒的主人哈尔致力于吸收年轻女孩的灵魂，所以镇上的女孩不敢靠近。
The story of the movie is somewhat based on the plot of the most recent game, "Sakura Wars 3," released back in March this year. While the game features Lieutenant Ohgami, the main character who takes off for Paris, narrates one side of the story, the movie unveils the secrets behind Hanagumi. Ohgami leaves for Paris, consequently leaving Hanagumi without a leader; thus a new character will be introduced here. To be replaced with Lieutenant Ohgami is the former leader of Hoshigumi, Rachette Artile - a rationalistic and distinct individual, who brings about serious problems to Hanagumi. The members are now in discord with Rachette. Meanwhile, Teikoku Kagekidan was being threatened by some irrelevant demons and a new type of anti-kouma mechas, (brought by an american company) appears and tries to replace the koubu-kai. Having made repeated mistakes due to the absence of Ohgami, Hanagumi is now faced with an unprecedented danger, while the abolishment of Teikoku Kagekidan Hanagumi is being schemed.
