Hi, I am writing this review to make things clearer for those who are confused about this OVA and Gekidol. The first part of this OVA is Gekidol´s episode 01. The second part is a completely random event ​set in a situation similar to Gakougurashi (zombies+girls+survival). I suggest read the synopsis so just you can have a better idea. There is not much to talk about this OVA. About the second part specifically: - Potential (enjoyable) friendships are there; - A few silly scenes yet a few 'oh~ I might enjoy this'; - The ending is a big cliffhanger, probably saying "go read thesource material - manga; already finished with 18 chapters".

The second part is barely related to the plot of Gekidol. It will touch in the matter just for a brief moment in one of the Gekidol episodes.
In a few details: Gekidol is related to theater/acting, so there's a brief moment where the cast from Gekidol will do a theater performance based in Alice in Deadly School events (which is the second part of this OVA).

In short, watching this is not necessary if you want to watch Gekidol.

That is it ^^