My first impression was that the Tensei Shitara Ken Deshita books were a joke series like Smartphone. I only ended up giving it a chance because I saw it mentioned positively somewhere else (I thought it was in Hell Mode‘s afterword, but after doublechecking that doesn’t seem to be the case).
Turns out it’s a mix of power fantasy and battle shounen elements that takes after Tensura in a number of ways, and while the beginning is a little rough, it starts picking up around the 4th novel (which also happens to be the peak of the inevitable cooking subtheme) and stays remarkably engaging up through the 7th. There are still issues of course (such as the protagonist being something of a halfwit)… but it’s definitely good enough as a time waster.
Unfortunately that all changes in the 8th novel and beyond, which perhaps not incidentally is where the first cliffhanger shows up.
The battles lose their sense of balance, with the protagonist suddenly struggling against C-class threats when they themselves are supposedly A-rank in power. Then an S-class threat shows up and gets stomped… only for more S-class beings to show up and suddenly be ~shockingly~ powerful. There’s also far, far too much exposition. Just a complete deluge of villain monologues and random backstory.
The 10th novel at first looked like it was getting back on track post-repairs, only to make it abundantly clear that the author has completely lost their grasp on the world’s mechanics. Fran and the sword became even more powerful than they were earlier (when they were fighting S-class threats), yet struggle and nearly die against an enemy that’s weaker than one they faced back toward the beginning of the series.
Nope, sorry, but I don’t see any way out of this recursively unbalanced power level situation.