Now, the Y row would be やいゆえよ, and the WA row would be わいうえを, so the same characters are omitted. However, the old version of these rows had different characters. Please take a look at these wikipedia pagese. I think the first one can explain a bit about your question, and you can see the old version in the second one. in English https://en.m.wikipedia.org/wiki/Gojūon in Japanese https://ja.m.wikipedia.org/wiki/五十音 I hope this was helpful.

They used to have more in the w section, わ、ゐ、ゑ、を.　"wu" never existed, as well as the ye and yi kana.