Why the Hell Are You Here, Teacher?! Vol. 9 (Kodansha, 2021)

From the ""route branch"" at the end of Volume 8, we dive into the what-if scenario where Tadashi picks shut-in mad scientist Nana Nanjo as his lover! Despite becoming a formal couple, their ""love level"" (as measured by yet another of Nanjo's wacky inventions) is only at ten percent. Before long, though, Tadashi's sister Kokoro and nosy teacher Hazakura find a way for the pair to live together in the girls' school again. Their exciting, romantic tale unfolds across ten chapters, along with a bonus character profile section!