I just checked my files and realized that I actually have the first 4 subbed episodes of the first ESPer series. The versions I have are from Aozora subs, and from looking at their LiveJournal page, they still have not yet finished it (though they have made significant progress since the series ended in 2013). Sadly though, they only allow people that they allow into their online community to access/download the sub files. They used to put hardsubbed versions on the D-Addicts torrent tracker (which was where I got the 4 episodes that I currently have), however D-Addicts shut down their tracker last year.
Would anyone happen to know if another/different group did english subs for it? I'd prefer hardsubs, but softsubs would be fine as well, as getting the raw/unsubbed episodes would not be difficult. It would just be nice to be able to watch the series in full before this sequel/spin-off happens.