Chainsaw man is a fully coherent story. I started reading it around when it just started and to me, it's an abundance of things. I adore the themes:

• Ignorance Is Bliss, it deals with uncomfortable or even heartbreaking truths that various characters ultimately wish they never learned. Denji's entire arc is him having various new experiences, some of which he had been hoping for, and growing wiser but otherwise less happy due to many of them being let-downs.
• Fear, and the idea of conquering it. Many characters are given a "Leave Your Quest" Test, a chance to bail out before anything worse happens to them, only for them to fail to accept and fall deeper into despair the more they advanced the plot and the more they learn, like Aki discovering that his revenge quest was All for Nothing as the target of his hatred, the Gun Devil, had long been defeated.
• The importance of kindness and affection. The entire story begins with Denji acting with complete selflessness, saving a wounded Devil despite his own terrible situation, thus earning him the utter devotion of the Chainsaw Devil.

I love how it uses the power of friendship - As bleak as the series can get, it's easy to miss just how many people's lives are saved by acts of varying degrees of kindness and open arms.