Jiro's group decide to take a work vacation inside a beachside dungeon, inviting Suera, a dark elf coworker and the vampire merchant Memoria. Meanwhile, Karen, one of the rival tester's group and the girl who gets killed first in 12.2, gets fed up with the shifting dynamics in her group and quits when she realizes the other two are hooking up. Jiro sees her miserable while at the beach and invites her to spend the day with his group to get over it. That evening, Memoria decides to become Jiro's second girlfriend. Obviously, your boy stumbles and stutters about it, but accepts and Suera does too. But then, the lights go off in their beachside bar and eventually the group realizes there's a coup going on. The elves realize that it's being performed by an anti-human faction trying to dismantle the testing program. The group helps out and eventually the uprising is suppressed.