School Rumble: Nee-san Jiken Desu!

Tsukamoto Tenma has to receive supplementary lessons starting from the very first day of summer vacation which was supposed to be full of fun. Upon arriving at the classroom, she finds a curious sight spreading before her eyes; Karasuma-kun is lying on the floor unconscious!
"Karasuma-kun! Don't die on me!"
With Tenma's grievous scream resonating through the place, a day of horrors draws the curtains.
Will the love of Tenma make an advance despite this chaotic situation!?