User is Akutagawa.

Atsushi smiled as Dazai finished tying his tie, his eyes glanced over at himself in the mirror. He watched as a Dazai smiled and tucked a flower in into his front suit pocket, it was a black rose picked out by Akutagawa himself. He wore a black suit, a fancy expensive suit he’d gotten.. he had to look nice after all.. it was his wedding.

Soon he was aloud to roam around as his bestman Dazai shared a cup of Chuuya’s expensive sake with him. "I’m guessing Chuuya’s helping dress Akutagawa?" He had asked only for Dazai to give him a thumbs up and a pat on the back.

Soon he snuck away stumbling across a room lit dimly with two voices inside. It was Chuuya who was Akutagawa’s bestman hyping up a clearly nervous Akutagawa.