Kumiko’s criticisms confuse
Toru. He never realized that Kumiko was so particular about certain types of food or the color of her tissues and toilet paper. Toru thinks that Kumiko is likely in a worse mood than normal because her period is coming soon.
Apparently, Kumiko’s menstrual cycle perfectly matches up with the cycle of the moon, so Toru always knows when to expect her period. After their argument, Kumiko confirms Toru’s theory and apologizes for her bad attitude. Later that night, as Kumiko and Toru lie next to each other in bed, Toru continues to wonder about whether it is possible to know another person’s essence.
At the moment, he feels like he does not know Kumiko at all.