Rika - Jisho 28 Sai no Junai Monster

A dead body in a suitcase is found on a mountain. The body is identified as Takao Honma. 3 years ago, he was kidnapped by Rika Amamiya and went missing. Detective Jiro Okuyama tries to catch Rika Amamiya. He uses a dating app, while using a fake name, and finally finds Rika Amamiya, but he becomes attracted to Rika Amamiya.