Ren was an orphan who was abandoned outside a port warehouse as soon as he was born. According to Nobuo Terashima, the incident was even reported in the news. Subsequently, he stayed at the same orphanage as Yasushi. After Yasu was adopted by the Takagis, Ren frequently visited his friend, so much so that Yasu's foster mother offered to adopt him, an offer which he refused. He kept living in the same warehouse that he was abandoned in. He thinks it makes him remember where he came from.