When I Turned Around, There He Was. In Karasuma's Name. All Mysteries Revealed!

S2 E13: It's every high schooler's worst nightmare... Exams! Abandon hope, all ye who enter the forsaken halls of Yagumi High!?! Harima finds himself haunted by the Flunk Out Phantom, a long dead teacher who appears only to failing students on the eve of their being held back. Wait, this can't be the first time Harima's seen this particular spirit! Tenma's not really seeing things, no more so than usual. She's just got her brain so full of Karasuma that there's no room left for any of her lessons! And what exactly has been lurking in the watery depths of the school swimming pool?!?