Notes
Handwriting recognition is hard, so this tool doesn't check if you got it
right at all.
There are some hiragana with ambiguous romanji. The hiragana for shi and
chi, with a " (dakuten), are pronounced the same: ji. Same for
the hiragana for su + " and tsu + ", both pronounced zu. See
Yotsugana for more
info. To work around this, I'm using du to represent tsu + ", and di to
represent chi + ".