I'm just a beginner in Nihongo, but I know the difference between the use of katakana and hiragana in sentences. Katakana is used for transliteration of foreign words, onomatopoeia, technical or scientific terms, or from emphasizing words, but why is "Encouragement of Climb" written as ヤマノススメ and not やまのすすめ? It didn't pass any criteria for it to be written in katakana.
There are a number of stylistic or aesthetic reasons to do so. Sometimes katakana is used for a native Japanese word because of the katakana's "international", "modern" or "high-tech" feeling:
However, katakana is also associated with oldness and tradition because it was the standard script in formal or academic documents in the Meiji era:
- Why is this written in katakana instead of hiragana?
- Orthography at the turn of the previous century
(This may seem contradictory, but in reality, other design choices such as fonts also matter.)
In this specific case, I think the latter image is more relevant. This book title is a parody of 学問のすすめ, a very famous book written 150 years ago, and one of the earlier copies was full of katakana, like this. By using katakana, the author is signaling that this ヤマノススメ is like a climbing version of the nationally famous classic.