I think it's too much for an 11-year old to completely dive in to the Japanese alphabet, considering that there are three sets of alphabets in Japanese and their usage varies greatly.
I've started learning since I was 7 (my Japanese uncle was teaching me), but it was never easy.
If you think it's too much, you can settle for an English tama now, or at least grab a very basic Japanese-language tama such as a P1/P2 or an Angel.
But if you really wanted to learn Japanese, I suggest you start learning how to speak it first before writing. Just a suggestion.