Ena Matsuoka is a Japanese idol, and part of the band Tenshitsukinukeniyomi.

Here they are.

And here she is.

Like most Instagram users, she often posts selfies and the like to update her fans on her day, and how she has been.

But one fan took it way too far.

Hibiki Sato used one of the photos the idol had posted on her social media page, and zoomed in to a train station reflected in her eyes.

He also figured out where she lived by using videos she had posted that inadvertently showed how her curtains were positioned, and how the light shone through the windows.

According to NHK, he then apparently tracked the station down using Google Maps, and basically waited for her there.

He picked a day when he knew she would be performing at a concert.

On September 1, 2019, Matsuoka was attacked from behind when she returned to her condominium in Tokyo.

Sato allegedly used a towel to cover her mouth, before pulling her to a dark corner and groping her.

The idol was injured during the incident, and Sato was arrested on suspicion of indecent assault.

Sato claims he was a big fan of Matsuoka.

Image via Tokyo Reporter and Twitter