Matsuoka, a member of the J-pop group Tenshitsukinukeniyomi, was ambushed by an obsessive fan who stalked her at her Tokyo home by using selfies she had uploaded to social media.

松岡笑南＠天使突抜ニ読ミ@matsuokaena

Hibiki Sato, an unemployed 26-year-old, waited for the singer to come home at a nearby bus stop and crept up behind her as she approached her door, covering her mouth with a rag before dragging her into a “dark corner” and molesting her, according to local media. A struggle ensued which left Matsuoka’s face injured.

Sato confessed to the crime when he was finally arrested on September 17, 16 days after the assault. Admitting he was an obsessive fan (“sasaeng” in Japanese), he explained how he had tracked her down using the photo. He even figured out which apartment was hers by analyzing the direction of the light and the type of curtains in the picture, he said.

Sato was indicted for the crime on Tuesday.