|Romaji||Z no ichiban nagai hi zenpen|
|Air Date||May 23, 2015|
|Episode Direction||Jiro Fujimoto|
|Storyboard||Tamura Kotaro, Matsumoto Rie|
|Animation Direction||Horikawa Koichi|
|← Episode 7||Episode 9 →|
Z's Longest Day (Part 1) (Zの一番長い日 前編, Z no ichiban nagai hi zenpen) is the 8th episode of Kekkai Sensen anime.
Zapp has spent his days leisurely until a Blood Breed appears at the city and he is tasked by his master to seal it off.