Complex sentence: The band held their first live in Eniwa just after the extended play's release, on February 15,2014 at the Eniwa Musōkan, where Fumito Iwai's high school band Guild first performed.
Split into simpler sentences: The band held their first live in Eniwa on the extended play's release date on February 15,2014. The live is to be held at the Eniwa Musōkan, where Fumito Iwai's high school band Guild first performed.