Warning! Spoilers ahead for Kaiju No. 8 chapter 45!
Some might view the manga Kaiju No. 8 as a knockoff of Attack On Titan, but it's successfully retelling the same story more effectively than Attack On Titan did.
Although an obvious nod to the Godzilla franchise, Kaiju No. 8 shares many similarities with Attack On Titan, namely for the fact that both protagonists - Kafka Hibino and Eren Yeager, respectively - can transform into their world's invading monsters. They both initially undergo tribunals when their secret is revealed and they both want to leverage their powers to ensure humanity's survival. But Kafka diverges from Eren in a number of key ways.
Unlike Eren Yeager who is celebrated for his proficiency in how he uses omni-directional mobility gear against Titans, Kafka is essentially useless as a human. Kaiju No. 8 capitalizes on these failures by creating circumstances that prevent him from transforming. Kafka is able to hide his identity as a Kaiju for a number of chapters while Eren is discovered almost immediately, causing Attack On Titan to circumvent crucial moments that Kaiju No. 8 ends up exploring, all so Eren can stand trial sooner. Meanwhile, Kafka must first undergo more character-defining events before he can receive his own sentencing. As a result, Kafka must rely on his subpar human abilities in battle and can only transform when he's off the radar.
While Eren and Kafka both want to protect humanity against their world's invading creatures, Kafka especially hungers to prove himself. He has been a failure for most of his life, having been rejected by the Defense Force numerous times before giving up on his dream to work at a job that involves cleaning up the remains of Kaiju. Kafka only applies to the Defense Force one last time after acquiring his Kaiju ability and is only accepted because he is suspected of being the series' eponymous numerated monster. Kafka might finally be a trooper, but his unique circumstances prevent him from gaining the recognition his Kaiju transformation could help him achieve.
Kafka and Eren also initially struggle with transforming successfully for different reasons. Eren originally fails whenever he either must fight against a former comrade turned traitor (which isn't a proprietary fear for Titans) or his desire to fulfill his goals isn't strong enough. But in Kafka's case, he is terrified of losing control because he could hurt his friends and keeps himself from transforming subconsciously in chapter 45, a fear he eventually overcomes when he realizes the capability of his fellow troops. Eren does lose control early on and attacks his childhood friend Mikasa, but the fear of this happening again oddly never prevents him from shifting. So far Kafka has only succumbed to his inner Kaiju once during his trial. If Kafka ever attacked or harmed any of his friends, it would likely destroy him, and he would undoubtedly give himself up to the Defense Force willingly to be executed.
While Kaiju No. 8 is obviously highly influenced by and borrows a great deal from Attack On Titan, the former improves upon many aspects of its predecessor that were glossed over. Readers are more inclined to root for Kafka on of him being a less than impressive soldier with more insecurities and failures Eren Yeager at the end of Attack On Titan.
