The new mayor of Kasukabe city, Mamoru Shizen, put great efforts into environmental protection, but actually he has an evil plan behind it. One day, Hiroshi and Misae drink a mysterious bottle that Shinchan has found from the riverside and they gradually transform into animals! The bottle is actually a drug that Shizen, the leader of “Save Keeping Beautiful Earth (SKBE)”, uses to change people into animals in order to halt the destruction of the environment. To save their parents, Shinchan and Himawari work with Kasukabe Defence Force and go to the headquarter of SKBE. Can they stop Shizen and save their families?

春日部新任市長‧四膳守積極推動環保措施，但原來背後有個秘密計劃… 某日，廣志同美冴飲咗小新喺河邊執返嚟嘅奇怪飲料，第二日竟然變成半獸人！原來四膳守一直研究實行極端環保措施「人類動物化計劃」，為咗令地球環境回復野生生態，佢透過「人類動物化飲料」將所有人類變成動物，從而阻止環境被破壞！小新、小葵、小白聯同春日部防衛隊成員，一齊前往敵人基地阻止四膳守，點知其他春日部防衛隊成員都開始半獸人化，而進一步變成動物嘅廣志同美冴更失去本性，忘記咗小新！到底小新、小葵同小白能否擊破四膳守嘅陰謀，並且拯救廣志同美冴？

春日部新任市长‧四膳守积极推动环保措施，但原来背后有个秘密计划… 某日，广志同美冴饮咗小新喺河边执返嚟嘅奇怪饮料，第二日竟然变成半兽人！原来四膳守一直研究实行极端环保措施“人类动物化计划”，为咗令地球环境回复野生生态，佢透过“人类动物化饮料”将所有人类变成动物，从而阻止环境被破坏！小新、小葵、小白联同春日部防卫队成员，一齐前往敌人基地阻止四膳守，点知其他春日部防卫队成员都开始半兽人化，而进一步变成动物嘅广志同美冴更失去本性，忘记咗小新！到底小新、小葵同小白能否击破四膳守嘅阴谋，并且拯救广志同美冴？