On the official website for the second season of Sound! Euphonium revealed a new key visual today which can be seen above. In the following link which will lead you to the main website, you will also see a listing of TV stations where the anime will be airing: http://anime-eupho.com/2nd/onair/. The second season will be releasing October and is a sequel of the first season that released April 8th 2015 and ended July 1st 2015 with 13 episodes. A recap movie was released for it on April 23rd 2016 as well. The series is based off of a novel series made in 2013 by Ayano Takeda. It would later get a manga that started November 28th 2014 and ended October 30th 2015 with 3 volumes released for it.
New characters for the series first include Mizore Yoroizuka whom will be voiced by Atsumi Tanezaki. Other roles for Atsumi include Nagi in Daitoshokan no Hitsujikai, Mei from High School Fleet and Lisa from Zankyou no Terror:
Our last of the new characters is Nozomi Kasaki. She will be voiced by Nao Touyama who has also voiced Rin from Bakuon!!, Claudia in Gakusen Toshi Asterisk, Karen from Kiniro Mosaic, Chitoge from Nisekoi and Yui from Yahari Ore no Seishun Love Comedy wa Machigatteiru:
Lastly is a plot summary below quoted from MAL:
After swearing off music due to an incident at the middle school regional brass band competition, euphonist Kumiko Oumae enters high school hoping for a fresh start. As fate would have it, she ends up being surrounded by people with an interest in the high school brass band. Kumiko finds the motivation she needs to make music once more with the help of her bandmates, some of whom are new like novice tubist Hazuki Katou; veteran contrabassist Sapphire Kawashima; and band vice president and fellow euphonist Asuka Tanaka. Others are old friends, like Kumiko’s childhood friend and hornist-turned-trombonist Shuuichi Tsukamoto, and trumpeter and bandmate from middle school, Reina Kousaka.However, in the band itself, chaos reigns supreme. Despite their intention to qualify for the national band competition, as they currently are, just competing in the local festival will be a challenge—unless the new band advisor Noboru Taki does something about it.From the studio that animated Suzumiya Haruhi no Yuuutsu, Kyoto Animation’s Hibike! Euphonium is a fresh and musical take on the slice-of-life staple that is the high school student’s struggle to deal with their past, find romance, and realize their dreams and aspirations.