Toshoku
Toshoku (当職,Tōshoku) is japanese first person pronoun.
Overview
It corresponds to the I, my, etc. in English. This word is so unique that ordinary japanese speakers don't use it.
Takahiro Karasawa had used it a lot in some tweet, then it has been known to the koushinists.
Koushinists use this word instead to ordinary first person pronoun like 当職は(I), 当職の(my).