What follows, contains spoilers, but only of the backstory to give perspective:
The story is fantastic. Some of the themes may be difficult to discern at first so I will be clear here my take on it. Homunculus is a story about a man that was ugly and ended up getting plastic surgery to better his life. This theme has been explored many times, but nothing like Homunculus. Homunculus deals with the mental breakdown of everything feeling fake. Nakoshi, the main character, achieved the great riches and the status he wanted, but he was never satisfied. Everything he had, had felt built up on how differently people treated him after he became better looking. It felt like nobody loved or cared about him for what he really is. This brings him eventually to a mental breakdown, and he throws everything away and becomes homeless. This brings us to the start of the manga, with this perspective in mind, the themes are much more clear. The trepanation is used to explore various themes surrounding the other characters and himself, it is also a form of escapism from Nakoshi's own problems. Despite being homeless for instance, he can't bring himself to make a decision of what he truly wants, he lives between his ultra wealthy past and a homeless encampment physically.
I greatly enjoyed symbolism with this and believe the work is by far best enjoyed viewing it as a whole instead of its parts. The themes were excellent and have stuck with me for many years, making this truly one of my favorite manga of all time. The difficulties we deal with in day to day life, would it be worth not being ourselves any more if we could artificially solve them all?
Overall this is a timeless manga. It provides many themes for the reader to think about. I just gave my example of what was most meaningful to me, but there are plenty other themes to discover throughout this brilliant work.
