The audio is from the live performance of Mamoru Miyano and Kishou Taniyama.Mamoru Miyano was the one who voices Dazai Osamu in Bungou stray Dogs and Kishou Taniyama was the one who voices Chuuya Nakahara.
See the link below to the liv video.

Song:CORONA - Kouka - CORONA

Anime: La Corda d'Oro: Secondo Passo
(Kin-iro no Corda - secondo passo)

Artist:Kishou Taniyama & Mamoru Miyano

Album: La Corda d'Oro Secondo Passo - Felice 2

Renders:Nakahara Chuuya & Osamu Dazai

Anime/Render:Bungou Stray Dogs

///////////////////////////////////////////
COPYRIGHT DISCLAIMER

Copyright Disclaimer Under Section 107 of the Copyright Act 1976, allowance is made for "fair use" for purposes such as criticism, comment, news reporting, teaching, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.

AKA:I do not own anything except for my editing.It all belongs to its respective owners.My purpose for using the song is to revive back the song of Kishou Taniyama.

LINK FOR THE LIVE VIDEO:
https://youtu.be/rgyCvVWY0hw

//////////////////////////////////////////
NEXT SONG: Young Boy,Run Under the Moonlight