Haha, that was awesome! Especially liked the ending. I'm going to be honest, I really liked it. This is pretty different from the type of story I normally read, but I still felt engaged! The beginning felt a bit slow to be honest (the introductory chapters were great, but otherwise), but the more I read, the better it got. The world's background almost reminds me of a crossmix of Fate and Men In Black. I will admit, the amount of characters could get a bit overwhelming at times, but I eased into it, and the story really shines in those quieter moments, before it all takes that and throws it into something new.
Also, the concepts for the worlds were really creative! Humans that evolved from chimps instead of apes, the world of the catgirl hero (no spoilers hehe), the rat people world...all amazing concepts. And I'll be honest, while it's not for everyone, I liked the fanservicy bits.
Of course, a full review isn't complete without the characters, which I must say I absolutely love as well. I...I feel Ken. I really do.
I've heard there's a sequel coming! I'm excited for that.