This 'test' for Kafka was kinda dumb. He clearly didn't want to fight, but the director forced and provoked him to by trying to kill him and the director's immediately like 'guess he's an animal after all' once Kafka's fighting back. Like, no shit Kafka's fighting back and lost control. What'd you expect? For him to just sit back and let you take his life? Even if Kafka was still in full control of his Kaiju side, his behaviour would still make sense.
Enjoyable anime, but, for me, doesn't really stand out among many other battle shounen. It's fine. Kafka being an adult was nice, but he may as well have been a teenager imo. The OP song was fine, but the ED was awful. Bog standard western pop that didn't fit the show at all imo.