A man who ran a website offering to help people commit suicide has been arrested on suspicion of killing a woman, Japanese officials say.
Sayaka Nishizawa, 21, posted a message to Kazunari Saito saying she wanted to die, local media reported.
Mr Saito is accused of giving sleeping pills to the woman and then suffocating her after she paid him 200,000 yen (£850), police say.
Ms Nishizawa, from Kawasaki near Tokyo, was found in her apartment on 16 April.
Detectives reportedly became suspicious because her house keys and mobile phone were missing.
Correspondents say websites giving tips on suicide are becoming increasingly common in Japan - a country already blighted by one of the highest suicide rates in the world.