When I learned the kana, I found some katakana characters more intuitive to remember because they looked so similar to the Roman alphabet that we use in European languages. In fact there are so many kana reminiscent of romaji that I came to wonder if the Japanese didn't lay hands on documents from Europe to find their inspiration. I know that officially the Japanese say that they simplified Chinese characters, but when I see the supposed source, I have my doubts. Western characters are often much closer. They could have seen some Roman coins that had reached Japan via China or India, who both traded with the Romans. Who knows ? Just look at the similarities :

ア = A a
イ = I
エ = E

カ, キ, ク and ケ all look a lot like K k. Just rearrange a bit the strokes and that's it.

チ, テ and ト look as if they were styled on a T or t. テ is really just a T with an additional bar on top. チ is a twisted T with a bar in the middle. ト is a t badly written.

ヤ is like a badly hand-written Y.

After all, the kana order was copied on Sanskrit, so why not a Roman or Greek influence ? Greek characters are also quite close.

ヨ (yo) is like a ω (omega) rotated 90 degree and made more square.

セ (se) is not unlike Σ (sigma).

More impressive, the Japanese キ is almost identical to the Phoenician , pronounced "xi" (written Ξ in Greek).

The Phoenician Yodh () and He () could both have been the source of the katakana ユ and ヨ.

Even ア looks uncannily like a Phoenician Aleph (), more so than the Greco-Roman "A".