Why are the episodes named after literary works?

Question

I noticed every episode of Parasyte, with the exception of the last one (which shares the title of the anime, Parasyte), is named after a literary work:

1. The Metamorphosis, Franz Kafka

2. The Devil in the Flesh, Raymond Radiguet

3. Symposium, Plato

4. Tangled Hair, Akiko Yosano

5. The Stranger, Albert Camus

6. The Sun Also Rises, Ernest Hemingway

7. A Dark Night's Passing, Shiga Naoya

8. Freezing Point, Ayako Miura

9. Beyond Good and Evil, Friedrich Nietzsche

10. What Mad Universe, Fredric Brown

11. The Blue Bird, Maurice Maeterlinck

12. Heart, Natsume Souseki

13. Hello Sadness, Françoise Sagan

14. The Selfish Gene, Richard Dawkins

15. Something Wicked This Way Comes, Ray Bradbury

16. Happy Family, Lu Xun

17. The Adventure of the Dying Detective, Arthur Conan Doyle

18. More Than Human, Theodore Sturgeon

19. In Cold Blood, Truman Capote

20. Crime and Punishment, Fyodor Dostoyevsky

21. Sex and Spirit, Clifford Bishop ^{(this is the only one I am unsure of, since no link is available yet on the wikipedia page on the anime, so I had to do some research)}

22. Quiescence and Awakening

23. Life and Oath

Why do the episode have these works' titles as their own? Were these significant pieces of literature for Parasyte's creator?
Or are the titles somehow related to what happens on each episode? I can see the relation in the first two episodes, the 5th, the 15th and the 20th. But I don't recall precisely what events happened in other episodes, so I can't compare them to the titles (also because I hadn't noticed they were references before).
Also related, and may help to answer the other questions: were these titles chosen solely for the anime or do the chapters (or at least some of them) use them too?

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EDIT

I found a post on reddit that says:

And the name of the first episode, Metamorphosis, is writer Hitoshi Iwaaki's inspiration for the whole series.

There is no source or reference backing that up, though.
Just edited that in so that there's at least somewhere to start looking, if the claim in the post is correct.

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EDIT 2

The latest two episodes still aren't referenced in Wikipedia, and I have no idea what work they could be alluding to. If anyone knows what piece of literature they are a reference to, please edit my post accordingly.

Answer 1

Here's a partial answer pertaining to episodes 21-24.

Recall that the Japanese title of the anime is "Kiseijuu - Sei no Kakuritsu", or loosely, "Parasyte - the probability of sei". The title is written in Japanese with sei in katakana, which is a non-semantic syllabary, rather than in kanji. This makes it unclear what the intended meaning of the word sei is, because there are at least 30 different kanji (based on a quick look here) that can be read sei (and hence around the same number of distinct meanings for the word), and it is not possible to infer from context which one is intended.

This ties into the titles of episodes 21-23, which are all pronounced "Sei to Sei" in Japanese, but using different characters for each distinct sei. Specifically, episode 21 has 性 "sex" and 聖 "holy"; episode 22 has 静 "quietness" and 醒 "wakefulness"; and episode 23 has 生 "life" and 誓 "vowing" (生 "life" is the same sei as in "kiseijuu", incidentally).

These three titles constitute a sort of wordplay, in my opinion. This sort of homophone-based wordplay is fairly common in Japanese, since Japanese is a very homophone-rich language, owing mostly to heavy borrowing from Chinese.

I strongly suspect that it is only coincidental that the Japanese translation of the English book "Sex and Spirit" by Clifford Bishop has the same title as episode 21 of the anime (judging from the synopses of the book available, anyway). Given that the book is only a penny on Amazon, the interested reader might like to pick up a copy of it and see if there is, in fact, any thematic relationship with Parasyte.

This being the case, I do not believe that the titles of episodes 21-23 reference literary works, other than coincidentally. And, of course, there's no literary reference in the episode 24 title 寄生獣 kiseijuu "Parasyte" - unless you count a title drop as a literary reference, I guess.

Answer 2

I haven't watched the anime (know very vaguely), but I have studied a couple of text you mentioned. Let's see...

Metamorphosis: Supremely weird and rather unnerving. It's a story of a man who one day wakes up to find that he has turned into a human-size cockroach. The story focuses on the transformation of one's humanity (hence, metamorphosis) in a surreal situation.

The Stranger: A work focuses on absurdity of life. We follow a man who is completely apathetic to everything, because there is no purpose to anything. He is not immoral, but due to his amoral, society condemns him anyway out of fear.

Nietzsche in general: I've read his 'Genealogy of Morality', figure it's not too different. He argues that there is a difference between the world 'bad' and 'evil', despite the fact that both words are the opposite of goodness. Basically, there's the evil of someone being immoral, and there is also the badness of someone being in your opposition. A lot of talks about masters and slaves here.

Hope this helps.