With isekai you mostly have a handful of types. The ones which are stereotypical; those that try to be original in the setting or powers of the protagonist (failing about half of the time); and those that only use the excuse of the isekai to present us some chill adventures, comedy or romance, etc.
Killer Shark in Another world... Its like a movie from The Asylum in manga format.
Whats The Asylum...? Did you ever saw a Sharknado movie? Well, they did those movies.
The series deals with Shiromi. A girl from a modest town that starts studying to be a summoner, and that way, helping to defeat the Demon King.
Sadly, she fails at summoning any useful creature. At least until she somehow ends up watching a movie from our work about a killing shark. Those gory memories interfere the next time she tries to summon something, resulting in Sa-Me appearing.
And despite it's funny appearance and how cute he acts around Shiromi. The little shark results to be a really powerful and violent being that doesnt doubt about attacking when provoqued -or not-.
The rest it's history.
I wont explain much more... Because there's little more lol.
This isn't a serious manga as you can obviously imagine. Just a gory stupid manga that parodies those bad movies about sharks, besides making a lot of references about american movies in general. To the point of absurdism.
So if you just want something funny and brainless, try this manga.