Katakana : ya-yu-yo

Let's take a look at just 3 characters the Y's.

As with Hiragana, modern Japanese doesn't use Yi or Ye.

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ヤ - ya - as in hiYA! This looks like a YAk stepped on something ユ- yu - as in YOU It looks like a number 1 - You are #1! ヨ- yo - as in YO! It's someone doing that gangster sign and saying YO!?

Write them out 10 times a day and soon you will get it. To aid memorization, make silly associations to go with them. You can use the above mnemonics or you can make your own!