What are the pen names ヰ and ゐ?

ゐヰ and ヰ are now abandoned Japanese pseudonyms, which are the second pseudonyms of わ, that is, wi, ゐ is written in Hiragana and ヰ is written in Katakana.

With the development of Japanese, the pronunciation of this Wi was gradually abandoned and replaced by a second pen name "Hiragana". In the past, some Chinese characters, such as Jing, Wei and Yi, were originally written under pseudonyms, but now they are all written as Yi (pronounced like Chinese characters).

Now these two pseudonyms can only be seen in some names (mostly old Japanese) or Japanese ancient books.