- Awesome Art: Not just the manga itself, but the rest of Rosca's art. For reference, here's two pics that she drew out of insomnia.
- Complete Monster: Miss Eleanor Weaver is the principal of Hollow Fields academy. In the past, after she succumbed to an incurable illness, she began practicing forbidden science, and tries to corrupt other doctors to her side. When her husband found out, she then transferred his consciousness into a mechanical box while having his body destroyed. After becoming the principal for more than a hundred years and seeing the bodies of her subordinates—better known as Engineers—begin to deteriorate, Miss Weaver made a deal, where the students were unable to leave Hollow Fields after graduation, and anyone with the lowest scores would be sent into "The Windmill". It was soon revealed that the children that were sent to "The Windmill" are being experimented on, so that she could transfer the Engineers' consciousness into the children, and when that failed, they essentially lost their memories, becoming hordes of zombies. Due to the extreme impatience of the Engineers, Miss Weaver tries to eliminate both the Engineers and the children of Hollow Fields with Rocket Engines as a last resort. Motivated solely on increasing the reputation of the school more than anything else, Miss Weaver is the most depraved of all Engineers.
- Iron Woobie
- Lucy Snow is bullied by students and teachers alike, and is constantly on the verge of beng sent to detention even when she's an ace student. In spite of her circumstances, she buckles down and masters what she's taught to become a Guile Hero.
- Inverted with Claude, a Determinator that doesn't become The Woobie until he has his chain yanked at the end.
- Jerkass Woobie
- Stinch. In a setting full of geniuses - evil or otherwise - he stands out for being exceptionally dumb, and the other characters are all too aware of this: the savvier children don't take his authority seriously, and the Engineers take his loyalty for granted. He becomes aware of this and has a Villainous Breakdown during the climax.
- Carmen. She's only a Jerkass because of her unfortunate friendship with Summer; she is an otherwise meek girl who would rather avoid conflict, and is genuinely protective of her friends.
- Love to Hate: All of the Engineers, along with Summer Polanski.
- Moe: Lucy Snow is adorably naive... until she begins mastering mad science and develops a more assertive personality. The opposite happens to Carmen.
- Nightmare Fuel
- Ugly Cute: Stinch
YMMV / Hollow Fields