The investigation of Hakuya’s murder is led by Yui Uehara, Taka'aki Morofushi, and Kansuke Yamato of the Nagano Prefectural Police Department. Hakuya bashed the back of his head, fell in the tub after losing consciousness and drowned. The discoloration of the bath water is due to the bath salts. Alibis and suspect whereabouts are taken; Tamami was preparing dinner, Sumika was vacuuming rooms and Jinsuke went shopping.