I'm pretty sure this (or at least sticking to kana) was attempted shortly after ...

		lkjhdcba on Aug 17, 2019 \| parent \| context \| favorite \| on: The most frequent 777 characters give 90% coverage... I'm pretty sure this (or at least sticking to kana) was attempted shortly after 1945 but was abandoned because of the sheer number of homophones.