So... I'm looking for this manga that I read about 4 years ago (I think it was 2010) — the main thing that I remember is that it mentioned the book No Longer Human by Osamu Dazai. I know this is super super obscure, but maybe one of you amazing people knows what I'm talking about?

Other things I possibly know:
- I think it may have also mentioned I Am a Cat by Soseki Natsume?
- The main character was a twenty-something man and his love interest was older (maybe forties?)
- If I had to guess length, I think it might have been a one volume series, and not a one shot.
- I remember the mood being kinda serious — it probably wasn't a comedy.

Any ideas?

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