So I'm a Spider, So What?, Vol. 13 (Manga) - Okina Baba

In the midst of an ancient ruin (that look more like a spaceship than a ruin) our party boldly makes their way!! But, uhh, we make have accidentally awakened a weapon from the distant past...or would it be future? I mean, it does look like a UFO...Agh, not another last boss fight!! IT'S THE EEEND OF THE WOOORLD AS WE KNOW IT! Well, not actually. Or at least not yet. While me and the Demon Lord and our band of merrymen tromped along the never-ending path to the Demon Realm, we found mysterious ancient ruins that house...a UFO? And 'cos this is my life--where everything that can go wrong does-- now I gotta join forces with the Demon Lord, Güli-Güli, some random priest guy, and our worst nemesis to avoid world annihilation..