RiderFan said: Blunt force trauma rarely causes lacerations. You'd have to smash your skull into shards and have those pierce your skin.
At the risk of applying physics to a rifyu comic, I'm guessing it's an abrasion of the forehead from moving her head so quickly that it scraped lengthwise across the desk.
As with scalp wounds, even a small wound of this sort would probably bleed profusely, as seen.
Blunt force trauma rarely causes lacerations. You'd have to smash your skull into shards and have those pierce your skin.
I mean, she is a Mahou Shojo, so she probably has the strength to bang it that hard...
Owwwww, my head hurts!I'm taking her to the nurse's office!Oh, you, Sayaka!My head hurts, may I go to the nurse's office?I pretended to be sick so we'd be alone together.