The Nurse. Ugh, she makes me gag. Always hopelessly flirting with Senpai. She's next on my list. Sorry, Muja, but you must be... fired.

She is a rather tough rival, but if I can just steal the cabinet keys... I could get the poison! Beat her at her own game.
I stealthily sneak into Nurse's Office. Without making any sounds, I grab the keys. Time for a distraction. I tap the Nurse on the shoulder.
"Excuse me, but I think Kokona is sick. Can you go and find her?" The Nurse sighs.
"Of course, Ayano. You two are friends." She scurries off, leaving me alone. I take a syringe from a cabinet and suck in the Poison. I hear the Nurse's footsteps and hide it in my pocket.

"Ayano, do not worry, she was just a bit pale because she's tired. It's fine." I close the door and take out the syringe. The Nurse frowns. All the practicing with the Martial Arts Club better pay off.
I run up to her, and inject the Poison. She struggles, but it soon takes affect. She's gone and won't be "taking care" of my Senpai anytime soon. I leave her on a bed and go to the Occult Club. Oka will be glad to be reunited with the Demons in Hell.