Deluge: hydras can be adventurers too

In the swamp, the rules are simple: you eat them, or they eat you. Nothing's ever that simple when humans get involved. They feed you weird potions, teach you ridiculous commands, and make you fight pointless fights with totally unfair enemies. The humans are insane. Nothing they do makes sense.

After years of—very much non-consensual—experimentation, and a dark ritual involving goat's blood, System decided to reclassify Deluge as sentient. A nice title, but not something you can eat.

Now, armed with heightened intelligence and slowly accumulating knowledge, you would think this artificial world would finally start to make sense. Turns out, no. It makes even less sense now! The more he learns, the more absurd it gets: civilization, laws, status, guilds, oaths - it's all just random nonsense!

There's only one system that Deluge respects, and that's System. System gives you levels. System gives you power. 

Note from the author:

I'm writing this book because I've always liked the idea of a monster perspective story. Sadly, such stories typically progress by having the monster slowly turn human. First by learning to speak, and then by gaining a humanoid form. That always leaves me feeling cheated. The main character in this story will never learn to speak, read, write or even understand language beyond simple commands and individual words. With that said, he doesn't turn into a psychopath either. Mostly he just hisses at people.

The story is structured as a series of light novels. If you don't want to read anything incomplete, just read up to chapter 34, which is where volume 2 ends.