The story can start of confusing for some readers, but trust me and read it further. With the introduction to the immortal(caterpillar) the story starts to get intresting with the struggles of the caterpillar. At first the caterpillar just wants to live and along the way as it struggles to evovle before the 90 days limit it starts to have a grander purpose to be able to use magic when it evolved into the moth was its struggle than. With how the story progresses you can see that the immortal has a greater purpose, and are the other caterpillars with it also immortals? Or is the MC the only immortal reincarnated into a caterpillar, that still confuses me. And as for the second characters story i cannot really say much about it as it has not progressed much plot wise. But the grammar of the story is amazing and the highlight of this story would definitely be that the author is writning the stories of 2 characters simultaneously, not an easy feat. This unique writing style is what gives the story an edge.
But there are some negatives, and that would be the colour for some boxes as the text is not readable for the gold boxes when the text is white. Other than that there is nothing wrong with the story.
The prologue gave me a very dark souls origin vibe. While the introduction of the main character gave me a shounen vibe. Overall the plot of the story is good, nothing intresting so far cause the it is still new and not much has developed, I assume that once the story gets further and the plot thickens it will get intresting. Grammar wise a few mistake here and there, but I can't really judge since my grammar is bad as well. Character wise, I find the characters hard to visualise as there are alot of characters being introduced and very little descriptive words about the characters maybe its just me. But the best part about your light novel is the way you write your story, you have a unique way in changing scenes and explaining what is happening at a certain time in two different locations props to that. Keep writing as I see alot of room for growth plot wise.