In a horror story worthy of Halloween, Tokyo police have arrested a man after finding severed body parts of least nine victims in the bathroom of his apartment. The dismembered pieces were stored in a cooler and covered with cat litter.

The gruesome discovery was made in Zama city, some 40km from Tokyo, the Metropolitan Police Department in Tokyo said, as cited by the local media on Tuesday.

Police were searching the apartment of 27-year-old Takahiro Shiraishi in connection with the disappearance of 23-year-old woman, who was reportedly seeking an accomplice for the purpose of a suicide pact. After checking coolers and storage boxes in the apartment, police found severed body parts – including heads, legs and arms – belonging at least nine people. Eight of the victims were women, police added.

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“I severed the body in my apartment and put it in a cooler. I did so to conceal evidence that I killed the person,” the suspect told police, the Asahi Shimbun newspaper reported.

Shiraishi sliced his victim in his apartment between August 22 and October 30, and then put the evidence in a cooler and covered it with what is presumed to be cat litter, officers said. Police suspect that the man also killed another eight people and similarly dismembered their bodies in the apartment.

Police also found a saw, which the suspect presumably used to dismember his victims, Kyodo news reported.

The case was opened earlier in October when a man reported that his sister, 23, had been missing for several days. The woman from western Tokyo was reportedly looking for someone to join her in committing suicide: “I want to die, but doing so alone is terrible. I’m looking for someone to die with me,” she allegedly wrote on Twitter, as cited by Asahin Shimbun.

The woman exchanged messages with Shiraishi on a suicide website, the investigation discovered. CCTV cameras at two railway stations near Zama also captured the woman walking with a man who resembled Shiraishi.

“[At that time] I met her for the first time. I killed her,” Shiraishi reportedly told police. According to the investigators, the woman’s body was among those found in the suspect’s apartment. DNA analysis will establish for certain if the body found in the Shiraishi’s apartment is that of the missing woman.

Shiraishi’s neighbour said that the man moved to the apartment some two months ago, from which time he started noticing a strange smell. “It was an extremely pungent smell that I had never experienced [before],” the man said, as cited by Asahi Shimbun.

Another neighbour told Kyodo news that he could not believe that Shiraishi was a murderer. He was “a cheerful, kind and polite man. I cannot believe this,” he said.