Devin remembered that there were two monsters that attacked the painting museum.
Giant Red Rat and another monster that was too strong.
In the novel, Ava, Eri, and Elmer take care of the Giant Red Rat in five minutes. They are injured, but not too much. However, the next monster that appears almost kills Ava, Eri, and Elmer.
So, Devin wanted to leave after killing the Giant Red Rat, but because of an unstable factor of Tanya, the plan failed.
Five minutes, Devin just had five minutes to leave but he and others had to find Tanya before.
Although they were stronger than a novel, had more people than a novel, and weren't injured at all, Devin still wanted to leave and didn't want to fight.
Devin and others looked through the big painting museum, Eri was at entrance, looking at their to spot Tanya.
Four minutes passed, and they couldn't find the Tanya.
"She must have left the place, how about we also go out?" Devin said.