Rule 34 Dev - 10s 2016 2girls back-to-back black_hair brown_eyes brown_hair copyright_name dated euphonium fuuka_(fukasheu) hibike!_euphonium instrument kousaka_reina long_hair multiple_girls neckerchief oumae_kumiko pink_neckerchief purple_eyes school_uniform serafuku short_hair sitting smile twitter_username|7518486105