Showa Era, year 101, summer. Kanaha who was being attacked by a rampaging battle weapon requested the help of a strange boy who was sleeping in a coffin. That was the moment where the two secured a pact of master and servant. The boy called himself Kichuu—the army's strongest weapon?!

Haru wakes up as the only human in the world where Flowerian lives. After starting her school life, she heads to “Moon Garden Cemetery” to meet her mentor, Flowerian Alpha. Haru wishes to become friends with Alpha, who saved her life, but…? (Source: Plantopia Official Website)