What ultimately convinces Gwain to spare Geo - and what is one of the few things to perturb her - is Ami's Death Glare.
As Gwain explains just what the Golem Ring can do (it's a tool designed to help the user alter their weight), Geo activates it and plummets through the floor.
When Luna throws off her disguise, Agni prepares his video camera, fully expecting her to be naked underneath.
Luna's spherical robots are unleashed after a dodgeball confrontation between Geo and Agni's bullies. "Play ball" indeed.
Elsewhere, Electra finds one of the robots in the ladies' restroom, reading a newspaper.
Deva attempts to distract Luna by throwing a snowball in her face. Ami throws a carrot onto the snowball for good measure.
Mizu spends his time in class solving the overcomplicated formula that Luna made. He struggles a bit at first, though much later, it's shown that he solved it as he goes outside to seek out the now absent substitute.
He arrived at an unfortunate time, as Marlow, who was trying to point out Geo to the Principal, fingers Mizu instead. This happens again in the next episode.
Ami, having noticed Marlow stalking the group, shoots her down from a tree with an arrow. After Marlow falls down, nothing happens, and she attempts to walk away nonchalantly. Then the arrow's status effect kicks in when she goes offscreen, and she's out cold.
When Marlow questions her own conclusion of Geo being a vampire, Gwain performs some serious mental gymnastics to cover up the boy's humanity. From that point forward, everyone else believes that Geo is a vampire.
Geo finally sticks up for himself against Gwain's bigotry by licking her across the face. Sure, she embeds him into the doghouse he was sitting on during the scene, but she spends the rest of the morning washing her face in a nearby fountain.
It turns out that those bandits helped Luna hijack the train later on. The head bandit is, again, taken out by a Groin Attack, this time by Geo stepping on a metal bar.
Speaking of the train hijacking, when Luna finds the Engine Driver, he's...well, shocked. Very much so, to the point where he can't register that she's telling him to keep quiet. Eventually, she just gives up and throws him out, leaving him stranded on a sign. Did we mention his appearance is based off Sr. Pelo, and that he's 'voiced' by him?