ヤ

Think about the head of a yak, with the right-side point being the nose and the two points on the left being the horns. This character is spelled “ya” like the first two letters of “yak”, and sounds like “yah”.

ユ

Imagine the letter “u” has fallen onto its side. This character is spelled “yu” and sounds like the letter “u”.

ヨ

Imagine someone holding up three sideways fingers and saying “yo”. This character sounds like “yo”.