[yorwba]

The stereotypical French speaker who has trouble with English [h] would definitely have the same problem with the Japanese [h], [ç] and [ɸ]. If they can't manage the tongue placement for English [θ], how are they supposed to handle Japanese [ɕ] and [ʑ]? And that's just the consonants.

Usually when someone thinks that language X has all the sounds of language Y, it's a speaker of language X who hasn't yet realized that their ears are too attuned to language X to recognize the sounds of language Y as something different. Don't trust your ears!

[mytailorisrich]

It's only the letter H and R (as transcribed in romaji) that are not immediate for a French speaker but they are not difficult. Certainly much simpler than 'th' in English. (Source: not my ears but Japanese textbooks)

[yorwba]

How would a French speaker pronounce し [ɕi] and じ [ʑi]? My guess would be « chi » [ʃi] and « ji » [ʒi]. Close enough to be understood, but different enough to be noticeable.