I mean, it's published, 跳べない蛙, you can buy it on Amazon or wherever. But in Japanese.

Can ChatGPT translate a whole book now? Without too much inconvenience

I used it to read some webnovels a few months ago. It's much better than other machine translators (like google or deepl) but it's a bit tedious to use because of the character limit.

Sceptical that an LLM would produce good literary translations - that requires a nuanced understanding of the author's rhythm and style. Maybe if the model was trained only with writing from that one particular author.

Deepl might do a decent job and it supports pdfs and other document formats. We use it a lot for translating business documents and contracts. Mainly between German and English. But they support Japanese too.

Wonder if someone will pick this up and publish it in English.

Negociating with a Japanese publishing house is probably 3 times the effort of translating the text itself. I'm interested in the book myself and I can read some Japanese (and know people more proficient than me who could translate it), but that's a no go because of intellectual property.