Sayonara Zetsubou Sensei - Season 3 Episode 12

It's Valentine's Day and Kagerou is afraid to open his box, because he doesn't really know whether any girl had dedicated a love letter to him or had not. Nozomu tells hit not to open it, in order to create a Schrodinger's box, in which the possibilities of the presence of any letter and the possibilities of absence are both infinite. A missile drops on the school's field and the class tries despairingly to hide it. An interviewer is, in fact, going to come to the school. After purchasing all the houses and getting the ramen shop Rin notices how the flavour has changed because of changing of her new management.