There are three OVA draws that are unfair, but after reading the third OVA, I finally said that I need to continue, but why can't I find OVA4?

Those three episodes are not the OVA of No Trace, but the OVA of Modern Visual Culture Research Society, which exists as a TV series of Looking at Research Now.

There are indeed 26 complete animated scripts, but as a drama currently under study, the pictures of these three episodes are all found in the current study.

Therefore, these three episodes of OVA were actually specially produced for the production of "Research on Reality", and the other 23 episodes were not actually produced.