Although he strongly suspects the series' protagonist, Light Yagami, a high school genius and the son of detective superintendent Soichiro Yagami, one of the primary members of the Kira investigation allied with L, to be Kira's alter-ego, he is unable to prove his theory, due to lack of evidence, but nonetheless remains suspicious of Light and carefully observes him.
Although he strongly believes that the series' protagonist, Light Yagami, a high school genius and the son of detective superintendent Soichiro Yagami, one of the main members of the Kira investigation allied with L, is likely to be Kira's alter-ego, he lacks evidence to confirm his theory but remains vigilant towards Light.