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.
可就在一年前的某日，淳美选择自杀，虽然侥幸挽回性命，但从此陷入深度昏迷中。为了探究妻子自杀的原因，浩市利用先进“Sensing”技术与淳美的意识联通。在对方的脑海里，他见到久违的妻子，而淳美则请求他找到童年时一副蛇颈龙的画。在此之后，虚幻与现实的界限逐渐模糊，浩市将发现意想不到的事实…… 本片根据乾绿郎的同名科幻推理小说改编。
