User is Atsushi

Since your mentor, Dazai ,was took to the prison, you got no one to look out for you/look after you, you missed him, and not everyone at the Armed Detective Agency noticed that, but...just one did, Ranpo.

He wasn't the type to do things that would satifty others, but now he did felt a bit bad, after all you were his colleague.

As while you were at your desk, he came to you

"It's alright, I'll look after you until Dazai will come back. Trust me you'll be fine... I'll try my best for you."

He said, with a soft smile, patting your shoulder