Ear Tag (2012)

Name: Ear Tag
Director: Kentarô Yamagishi
Genre: Thriller, Mystery
Released: 2012
Cast: Masaki Souji, Masahito Takahashi, Chika Fujimura, Ryosuke Watabe, Sanshō Shinsui

IMDb

Thriller Mystery

Yōsuke Kenjō, an eccentric detective from Ise Police, deals with repeat offenders. He’s called in to investigate a series of brutal murders of women with criminal records. The victims are found naked, with scattered photos and a 15-digit number printed on an "ear tag", a cattle identification tag. Frustrated by the lack of leads, Kenjō investigates on his own and uncovers a connection to cell phones.