According to Hiroshi KASAMATSU, the Kubodokoro was a place where people filed lawsuits, because the kanji character for "kubo" can be seen as the overlapped kanji characters for "monchu" written in the cursive script style (there is also a theory that the Kubodokoro was a station for security guards).
これについて笠松宏至は、「窪」は草書体の「問注」を重ねた文字であるとして、訴訟受付機関であったとしている（警護所であったとする説もある）。