After serving an after-school punishment, Kazuki Muto is pursued by Mita, a professor at Kazuki's school that is revealed to be a homunculus that resembles a giant cobra. As he flees, Kazuki runs into his sister Mahiro who had gone to check on him. Kazuki tells Mahiro to run while he holds the homunculus off, but instead Mita emerges from the ground and swallows Mahiro whole.Kazuki attacks Mita in a blind rage, but realizes any attack is useless. He then realizes he must activate the alchemical powers within him to defeat the homunculus. As Kazuki activates his power, Mita swoops and swallows him as well.
Almost immediately afterwards, Kazuki bursts through Mita's body, brandishing a giant sword, with Mahiro in tow. Thus, the two are freed from Mita's stomach.
- This scenario was adapted into Episode 1 of the Buso Renkin anime