Run.
You take off at a sprint with no heed for where other than "Not where the giant bug-thing is". If you had the mental overhead for thinking, you'd probably think how this is the fastest you've run in your whole life, but right now all you care about is getting the fuck away from here at full pelt.
You manage to get a couple hundred meters away before falling into a... ditch? No, looking at it it's more of a trench, that you didn't notice due to the moss growing over it.
Muttering something about Isekai Bobbert crawls deeper (well as “deeper” as a dangerously fat man can get) under the woods
Right, you're in an anime now. Of course you are. It's the only logical explanation. Now that you've determined that you can work on the next step: Living long enough to get to your inevitable power-up scene. You start wedging yourself further next to the log before spotting a hole in it, just large enough for you to squeeze into. You commando-crawl as best as you can towards it and hide in there. As best as you can tell the whole thing's hollow and just wide enough to comfortable accommodate you.
Ok, this is too much for Caelia. Starts screaming and ducks into the moss, hands folded behind her head in a reflex.
You dive to the floor. The moss swallows you, providing quite a bit of concealment while you scream. The scream is almost entirely muffled, as best as you can tell the moss is absorbing the sound.
"Holy shit will you look at the size of that thing!"
Open fire on that big ass bug while moving towards some form of cover.
You train your sights on the giant bug-thing and start making a sideways jog towards the nearest cover you can. The bug still hasn't spotted you right until the first shot rings out. The bullet smacks into it and sends a spray of blood, a small amount compared to the thing but you have its attention.
For the first time it makes a noise. A deep hissing noise comes out of it and it stops running, stares in your direction as if determining whether you're worth the effort, then comes directly at you. You fire more shots, but the overall effect is minimal beyond possibly upsetting it more. You eventually come to the cover...
And see a pair of eyes peering out at you from inside the trunk, and someone muttering some words that sound like Japanese.